This guy is great. Very clear explanation, not too much information or too little. Straight forward and easy to understand. I even like the tone of his voice. Excellent.
Wonderful explanation! I just barely made it home a few hours ago (I ran the battery almost dry) and was dreading the inevitable confusion that erupts whenever I am faced with ohms, amps and volts. This video was a a lifesaver. I will head back to the shed with renewed confidence. Thank you so much for the help. Best wishes to all from Northern California. Stay well fellow Airheads!
Great video. Although I am an electrician and mechanic I found the explanations, in lay-person terms, to be most helpful for those weekend and not so experienced troubleshooters. Excellent job. My son and I, who have worked on hundreds of motorcycles, are going to be troubleshooting the charging system on a recently gifted R65 this morning so this crash course will come in handy even for us.
For years I've known this to be an easy problem to diagnose and to repair, but have yet to see it done in such basic, layman terms that the mere mortal can do ! No high tech terminology no stream of curse words for the sake of cursing. Just a calm gentleman showing a novice how to do it as of we were there one on one in his shop with a cuppa Rosie and perhaps and old dog laying by the heater, brilliant and many thanks from Calif ! If you ever get my way, I have an R75/6 you may use to tour the sights !
Watched this video...All the wiring checks I did pointed to the rotor needing replacing so I got a new rotor from Motorworks...Who I must add were really helpful when I visited them...So checked a few of the connections which all seemed to be fine...After the rotor was installed I checked on the off chance to see if there was a spark...and there was...So I fired up the old girl and she responded straight away...So now I have her running...If an open circuit rotor was an issue I am a bit confused as to what was wrong with the non-sparking issue but at least she runs now...Thanks again for all your instruction videos on these beautiful bikes...They are so helpful!
I’m pleased to hear that you have got the issues sorted. For sure an open circuit rotor will not affect the ignition system so long as the battery has sufficient charge. But the main thing is that your bike is now working. Thanks for the kind comments. All the best for the future.
Thanks a lot for a very clear, down-to-earth, no-nonsense video! And for not having any fancy music, logos, or intros in it, either. So, make more of these, please! Airhead electrics can be a bit mysterious to some of us, so this is really useful, at least to me; my bike is a 1983 R100RS, but the electrics are basically the same. ;-)
Thank you for the video. I'm currently rebuilding a R65 and only got a charge of 11.7 volts. I'll be using this method to check the rotor arm now as i have just checked the diode board and that seems to be working.
+Trikerbloke Turns out it was the regulator on mine. I made a quick video to show how I diagnosed it and put a link in to this video for the rotor. Hope thats alright.
4 years later and I'm here again...Sorry to be a pain again...R100GS (1990)...Haven't run the bike since last year and bought a new battery yesterday...Issues with the charging again...Battery light stays on (but dim) during running...I checked the battery posts while the bike was running but the voltage does not go up...I checked the rotor and that was new 4 years ago and is ok using your test...The actual alternator came off with a little persuasion but I noticed that the wiring mesh on the back is slightly loose although not too bad and not unconnected...I did run the multimeter on the 0-200K (same as for the rotor) and used it to see if the wiring on the actual alternator was ok and I got a reading from the red and blue but not the white one...One thing I did notice is that my wiring on the rotor is different from the one in the video - the red and blue wires are the other way around on mine...I'm hoping I didn't get them mixed up when I did this 4 years ago (I dont think so) ...Anyway...Any ideas...Thank you for any help
The battery was actually dry when I checked it this year which was a bit of a shock as it was a new battery last year...I've been a carer since xmas for my step-father this year up to a month ago, hence no biking
There's a sharp bend of the coil where it connects to the slip ring. There was a remanufacturing supplier who rewinds them taking out the bend making the rotor more reliable
AThank you for a very well presented and structured account of how to do the magic. I can't wait to get the old girl back home and get her sorted. Keep up the good work. Dave Holden.
I have done all checks from this video. Easy to understand and most importantly clear vocal. I had narrowed down the fault from the brown wire into the bulb, but cant find the reason why the bulb doesnt go off during high rpm. Im using a 450watts Endura with its’ upgraded diode board btw.
Thanks for the video! My gen light was going intermittently on my /5 so I used your process to troubleshoot it. Turns out my brush wires had come unsoldered and were just rattling around loosely in their holes. Got them soldered up and pulling 13.6v at 3500 rpm. I'm still going to eventually upgrade to the EnDuraLast 450w system, but this will delay that process for a while now.
Thanks for the informative video, I was looking to see what the rotor removal tool looked like. One thing I failed to notice ( I may have missed it) is that you made no mention of the slip rings being glazed-over. This would also give an open-circuit reading, but could be rectified with fine wet/dry paper to clean them, and not need a replacement rotor. Best regards Iain
Thanks for the comment Iain. I usually clean slip rings and commutators with an abrasive 'nylon' pot scourer followed with a wipe over with an alcohol soaked rag to degrease. Which is what I seem to recall doing on this occasion. I use this method instead of abrasive paper to reduce the chance of 'grit' off the paper becoming embedded in the slip ring. Alternatively, I have used a commercially available switch cleaner.
Thanks for the video. Had the battery on my 1990 R100GS go flat. Battery recharged OK. Used your process to check the problem and turned out to be the rotor open circuit. Luckily had a spare rotor and extractor bolt to hand and it took me 80 minutes work to analyse and replace. Super. Now I just need a video to explain the reason for having a warning light that fails to indicate a lack of charging, when the alternator wiring fails.
I'm pleased you found the video helpful. To get around the design weakness you in this system, you could always fit a voltmeter; if my memory serves correctly, BMW did offer a voltmeter as an accessory to fit the early GSs. Alternatively you could fit a battery status monitor, available from AO services: www.aoservices.co.uk/index.htm I have had one for years on my GS PD, it works very well.
Hi posted an initial comment on general video, positive of course, just put the old girl back together. Shifting this stator was a bit of a challenge, until I compared it with the "new" one, I found a long jemmy with a "shallow" end angle and used this to get the whole lot moving. She fired up a treat. Only thing which have would made the vid A*+ would have been to linger a little on the three cable re-connect with better lighting. But first class effort, and if I hadn't been a numpty I would have remembered the order for myself. Keep up the good work.
This video is exceptional as well as the mechanic! Clear and concise, easy to understand and to follow. I have liked and subscribed and now I need to follow up on your other videos. You have my sincere thanks for your time and effort for sharing your knowledge and skill with us!
Thanks so much for this video...I am a whiz with mechanics but draw a total blank with electrics so this vid is perfect as a step by step walkthrough for folk like me...Thanks you
I've had an R90/6 for ~25 years. It's been very reliable and it's a sweet-riding machine. It's not nearly as fast as my R1200... but still nice for an old-timer.
I have a problem of the gen light on all the time and not charging battery. light off when ignition off. rotor has continuity with brushes not touching and the correct ohms reading. I have revved to over 3000rpm and light still on and no charge. 1981 r100rs Any suggestions ?
So the charging lamp indicates the balance of electrical output of the alternator with the battery. With the ignition switched on without the engine running electrical current flows from the battery through the ignition switch to the lamp and then the circuit continues through the rotor and back to the negative terminal via the motorcycle engine casing and frame. Under normal circumstances when the engine is running, the rotor develops a voltage in it’s windings that opposes the flow to the bulb from the battery and when the opposing voltage is high enough the lamp is extinguished: that is the voltage in each direction is balanced. This point at which this opposing voltage balances is also the point where the alternator output from the stator becomes greater than battery nominal voltage and hence the battery will be charging. If a fault develops, for example the stator stops working then the system will be out of balance and the lamp will come on, indicating that the battery is not charging.
Hey Moto! guess what? I found a 72 r60/5 in a dusty garage stored since '82 and 40k miles on it. silver vrs. Got it from an ex pat for about 1400 quid! light drop damage but I have it all working now and licensed. I will make vid soon, may need a starter relay and or starter button turn signal switch. I have the bare relay wrapped in rubber hanging below tank so I can trip the contact to start it when cold. No signal in relay when manually ground brown single wire. Fast bike! I also got the rt up to about 223kph smooth to 200 bit sketchy there after, rear rotor was warped new one fixed issues. found out it was police guys bike plenty of hi-pro motor work in it.
441rider wow! They are quite rare nowadays and £1400 is good value. Look forward to seeing a video. I guess temperatures are starting to drop now where you are. I’ll be leaving soon for what will probably be my last blast of the year soon. Off to Portugal to see my buddy for 2 or 3 weeks. I’ll try to post some video of the trip. Meanwhile I’ve just put up one about a home made emergency gear shift tool to use in case the selector pawl spring breaks on your 5 speed transmission (it’s known to happen).
Ahh the wire do-hicky to lift it into a gear. I will check out the vid. The r60/5 parts in good nick are few and far between and the headlight pin ignition board needs a good after market option. I want to keep it stock but it will be my city bike until I get the 441 bored and in the new frame. cold rain and short days already but a few sunny warm riding days still with the fall colours.
I have the eme upgrade and both my friend and myself have identical R100 pd with same problem: not charging. Any ideas before I start trashing another stator? Fred
thank you for video i have similar pb and i am gonna sort this out but you missed to say in the begining it could be also a faulty voltage regulator for this symptom i mean thegen lamp don t turn on
great video... i got the exact opposite problem i just put on a new charging system stator, rotor , voltage regulator .brushes and now my battery warning light is staying on anything i should trouble check ?
I have a few old airheads I am rebuilding, and they both seem to not charge very well. I am only getting about 12.9V at idle and about 13.2V at 2000 RPM on a healthy Shorai Battery. The rotor is only showing about 1.5-2.0 Ohms, (But that is not pulled off the bike - not sure that matters) Is that enough to give you a weak charge. The brushes seem fine but will replace those too. Thanks in advance.
To check the charge rate, first switch on the headlamp for 5 min without the engine running, then connect a multimeter set on the 0 - 20 volt scale to the battery. Leave the lights on and start the engine, observe the meter it should read between 13.5 and 14.5 V and then start to fall back as the battery charges up. Early airheads had slightly lower power generators. If you check in a workshop manual you will find the values correct for your generator. If the rotor resistance is low replace it. Resistance should be checked with the brushes not in contact with the slip rings. Slip a piece of paper between the brushes and ring when you check. May also be worth checking the regulator and rectifier next.
Hi, I have the opposite problem. When my ignition key is ON, the GEN lamp goes ON brightly, but it only fades a bit when the engine is revv'd up. I tested the diode board, the rotor and the rectifier and all are good. What else could it be the cause of the low charging?
Hi, sorry to learn that you are having trouble. You say that you have tested the diode board and the rectifier, but they are the same thing. Did you mean the voltage regulator? If you are sure that the components you have tested are functioning properly, then the only thing left is the stator. It is unusual for these to fail, but if they do they can either fail because one or more of the phase circuits has either got open circuit, or there is a short. Testing with an ohm meter should show either fault up. Good luck.
@@motophoenix5951 yes, sorry, I meant the regulator and the rectifier. What I did is replace the existing one with spare units that are good and that did not solve the problem. I made the measurements on the rotor and I have good readings. Concerning the stator, should I take measurements when mounted or dismounted and I guess at the 3 terminals to check if the stator is open or close, right?
My R100GS doesn't have an ignition spark...I haven't run the bike for a few years...The only light I have on the dash at the mo with a new battery is the green neutral light...The engine turns over but no spark....I know that the alternator wasn't charging when I last ran the bike...Could it be that the rotor on its own is at fault?...
No a faulty rotor will not affect the ignition system. If the bike has been laid up, it is probably a high resistance (dirt, oxidation) at a connection somewhere along the ignition circuit. I suggest you use a multi meter set at 0-20V dc, or use a12V bulb to probe live connections. Connect the black lead of the meter, or one side of the bulb to a good earth and probe connections with the other. If voltage drops or the bulb is dim/out the connection will need cleaning. If as you suggest, there is a supply to the ignition switch, start there and work your way along. Hope that helps.
hello sir, very interesting vid, tnk u so much!! ;) , i have the same problem with my R80RT and i have two questions: *you've disconnected the battery earth cable to open the cover, then you've reconnected it, Do u keep it that way and do all the next steps? *Do i have to change the rotor itself or the wire only? thank you again and hve a gd day!
Amine Makhlouf Hello, I only disconnect the battery to remove or refit the cover, since it is very easy to cause a short circuit by touching the cover on the rectifier (diode board), mounted above the alternator. This may result in overheating and damage to the electrical components. So, yes, reconnect the lead to carry out the next steps. If you can I would recommend replacing the rotor. However, you may be able to find an electrical specialist nearby who can rewind the old one. I have had this done in the past, but with limited success, since the rewound rotor did not last as long as the original Bosch item. Good luck with your repair.
great video and useful tips as well!I have a 1982 R100T which has a charging problem...I will leave the battery on a trickle charger overnight which will be fine for a few days but riding around will eventually drain the battery.battery is almost new from BMW, I have tested the rotor for resistance and it came back at 3.8 ohms, I shorted the regulator to see if it is the problem, once done I couldonly get 12V at around 3000rpm, i was under the impression that this procedure would give full output to the alternator..at least up to 14v or so but no luck even reving the engine it was stuck at 12v. once the plug was back in I got around 8V and generator light was on!!!any input you can share?thanks,Terry
Hi Terry. The resistance between slip rings on the rotor looks okay. Not sure what you did when you say you shorted the regulator, but you should have removed the regulator and bridged the D+ (blue wire) to the DF (blue/black wire) on the socket. Run the engine between 1000 and 2000 rpm briefly. If the charge lamp goes out, then the regulator is likely at fault. If not then you will need to look elsewhere, possibly the stator. You can check the stator winding resistance between phases; should be about 0.62 ohms. Between phases and earth should be open. Good luck.
Hello, thanks for the video really helpful for novice like me. My R100 is no longer charging, i check everything as described in your video and could not find any issue. I removed the rectifier and shunt the black and blue cable, then started the bike and battery was charging. I assumed that the rectifier was bad and bought a new one. After installing it, all was good, battery was charging. 3 weeks later same problem, battery not charging. It seems that the rectifier is again bad which i cannot really understand. Any idea why rectifier will go bad so quickly ? Any help would be appreciated
Hi, sorry to learn that you are having troubles with your charging system. I am a little confused by your terminology. You speak of replacing the rectifier (aka the diode board), but the test you have carried out relates to checking a possibly faulty regulator. So I assume you were talking about the regulator. Anyway, can we establish the circumstances of your non functioning charging system. Does the generator warning lamp stay on all the time? Or does the warning lamp not come on when the engine is stationary with the ignition on? Or is the warning light on all the time, but glowing very dimly; check this in low light conditions to be sure. Regulators do not often go wrong and from your initial description I suspect you may have a bad connection. Check for worn alternator brushes and/or dirty slip rings. Lift off the brush springs and pull out the brushes to establish that they are not worn out; minimum length 8mm. Inspect cable connections to make sure they are not generating a high resistance because they are dirty. When you have made these checks, get back to me. Regards...
Moto Phoenix hi, apologize for replying so late to you, I was on vacation. You are indeed correct, I meant the regulator located under the tank. First I have to say that the bike has been modified by the previous owner and that it does no longer has the original dashboard. A tachometer including LED’s has been fitted. The light on the dash glows as soon as I turn the key and stays on all the time, also while driving. I have performed following check: - battery voltage 12.4V - rotor front brush to rear brush, 3.9ohm, checked at the brush surface like in your video - rotor front brush to casing, nothing - rotor rear brush to casing, nothing - stator 0.6 ohm between each phase - stator, checking each phase to casing, nothing - Df cable (blue black) 0.3 ohm (stator side to regulator connector) - D- cable (braun) 0.5 ohm (stator side to regulator connector) - Y cable 0.3 ohm - D- connector on stator to rear brush 0.6 ohm - D- connector to front brush, nothing - Df connector on stator to front brush 0.4 ohm - Df connector to rear brush, nothing - ignition on and Df cable on stator side unplugged, dashboard light glows (I would have expected it to not glow) - ignition on and D- cable on stator side unplugged, dashboard light glows (I would have expected it to not glow) - regulator connector unplugged and ignition on, dashboard lamp does not glow - regulator connector unplugged and blue & blue/black bridged, ignition on, dashboard lamp glows - bike started with blue & blue/black connector on regulator connector bridged, battery voltage raising when accelerating - cleaned as best as possible the regulator connector and replugged to regulator, bike started, battery is charging and regulating to 13.9/14.2V I must say that I am a bit puzzled because I did unplugged the regulator connector in the past several times and it made no differences. What is more surprising is that I had the same issue 3 months ago and back then, I cleaned everything. Do you know how to remove each cable from the plastic connector so I can inspect each cable and cable shoe? I tried to push from the top but did not manage to get the cable out. Thanks again, Manuel
This was a fantastic video thank you... guess I need a new rotor. on another note... do you have a video about replacing or rebuilding the master cylinder on a 1976 R90/6? my bike has been sitting for a year and in diagnosis the rotor issue I noticed there is quite a leak in the master cylinder. thoughts. Thank you
+John Doe Thanks, I'm pleased the video helped. Unfortunately I do not have a video on how to repair a master cylinder. Some time in the future possibly. You could try Chris Harris for that. Here is a link: ruclips.net/channel/UCRZEzmVmi88hqnVKe7d-wIg
So if I did these tests and my Gen light never turned on, does that mean my Gen light is out? I was riding on the freeway and my 84 R100RS died as if someone hit the kill switch. Towed the bike home and tested the battery and it was at 10.59 and Gen light never turned on. Charged battery to 13.4 volts, completed tests in this video still no Gen light. Thanks in advance.
@@BIGGZ46if the bulb works when you test it independently and you have done the test I showed in the video, the next thing to do is to test if there is there a supply to the bulb? Use a voltmeter to test the live supply to the bulb when the ignition switch is on.
Hi, thanks for your video, it is very professional and educative. I was wondering if you knew what yo do when the GEN LIGHT is always ON? I have done every steps you showed on this video, I read a resistance of 2.7 ohms on stator, but very different with the brushes ( cannot remember well but around 67 ohms)> I changed the voltage regulator, and I also had a burnt red wire ( i think it is #86) going from the starter relay on the left side of the tank to the blinkers clip ( black clip with 6 wires). Would you know by any chance if there is a way of testing the relay with a multimeter? ( I will buy one whatever happens but for the future if it happens again) And also, should I replace that wire, knowing that I do not run any blinkers ( post 1985 motorcycle in New York state do not have to have blinkers). I really appreciate your videos, they are very helpful, and are much more easier to understand than reading a book. Cheers, Robin
+Robin Zeitoun To test the most common type of relay, connect each lead of your multi-meter to terminals 87 and 30 (doesn't matter which way round), then set the meter to the 0 - 200 ohm scale. The ohm meter should read open circuit, i. e. infinity. Leave the meter connected to terminals 87 and 30, then connect terminals 85 and 86 to the battery + and - terminals (doesn't matter which way round). You may then hear a click and see a very low value (almost 0) on the meter. When you break the battery circuit the meter should read infinity again. If the cable attached to 86 is burnt on your starter relay, replace the damaged piece of cable. Investigate and try to find out why it is burnt. Seems to me there may be a short. You do not mention which model you have but from memory I seem to recall 86 is live when the starter button is pressed and 85 goes to earth possibly via the clutch and/or side stand isolator. But you should check on a wiring diagram Regarding the Alternator, first you will need to have access to data about the alternator for the model of airhead you are working on. I suggest you get hold of a copy of the manual for BMW 2-valve twins 70 to 96, published by Haynes. At the beginning of chapter 10 you will find under the section headed Specifications the data you require in order to make comparisons with your own readings. Section 6 in the aforementioned chapter will guide you through a number of tests you can perform to help diagnose your problem. It is usually difficult to make a diagnosis of electrical faults from a distance and I think your best and quickest route lies with the use of your meter and a logical sequence of investigation as on offer from the Haynes manual. Hope that helps.
+Moto Phoenix Thanks a lot for your quick reply. I completely forgot to mention the year and model.. It s a 1984 R100 RT. About 60K miles on it. I found out why the red wire got burnt : Not long ago I disconnected that connector ( it was attached to blinkers, clock, and voltmeter), as I am turning the bike into a cafe racer and did not need any of the instruments nor the blinkers, although I reckon some water introduced itself in the connector that I left kind of hanging around, and shorted it... I am lucky it happened in front of me and was able to trace it to that wire that was useless at the time. As for the starter relay, I ended up buying a new one. It was probably the original one from 1984 by the look of it... Although I will get a Haynes manual, surely it will come in handy! Thanks again for your help, I will let you know how I go. Cheers!
+Moto Phoenix I ended up getting the clymer to find out what was wrong. I found the book very vague unfortunately, but I was able to identify very quickly that the diode board was faulty ( also thanks to you using the diode board testing videos you made). One of the diode burnt out ( Still trying to figure out why so it doesnt happen again, although I m thinking the battery is a bit old and also used a dry cell one a few times, which would have damaged it). I have another question for you ; I read on a few forums that the rubber mounts were not the greatest to keep on, so ended up buying the metal one for euro moto electric. BUT, to access the inner nuts, I might have to remove the starter motor. Would there be any other easier/quicker way that would not involved removing anything. I am pretty switched and capable of doing all that but from experience, if something works well and does not need to be moved, I would rather leave it where it is. Thanks again! Cheers, Robin
Hi Robin, diodes burn out occasionally. But it may be worth checking for a bad connection from the soldered joint melting, caused by the heating effect of the rectification process. I have had this happen to a couple of diodes on my 400 W generator set-up. I re-soldered the joint each time with old-fashioned plumber's solder (higher melting point), which appears to cure the issue. Personally, I am not adverse to rubber mounts, but they do fail from time to time. They are very awkward to change and I did fit the solid ones that came with my 400 W kit. I have managed successfully in the past by using a 1/4 drive socket that incorporated a u/j, but even then it's a fiddle. Or you could try holding the nut with needle nose pliers or magnet whilst you screw the mount onto the nut, then finish with a socket or spanner. Good luck
If you have to push the brushes onto the slip-ring to make the warning lamp illuminate, then it would seem to me that there is a poor connection between the brush and the slip-ring. The brush(es) may be excessively worn, the slip-rings may require cleaning or the brush spring may be weak/broken.
Moto Phoenix Thank you so much for the response. I’ve a puzzle I’m working on and I sure wish I had the expertise you do. I have a ‘76 r90/6. The gen light has always flickered on and off for the 6 years that I’ve owned it but it’s never left me stranded. Then, one night, it started to die as if it wasn’t getting enough fuel. (It had plenty of fuel) So I cranked it back up (the electric start struggled but it finally started) and it kept wanting to stall unless I revved the engine at high Rpms. I eventually had to stop at a red light and the bike stalled as soon as the RPMs dropped. The battery appeared to be so weak that it would even click when I pushed the start button. So I push started it and was able to limp it down the road a bit without the headlight on. The battery was just purchased that month and was tested after the bike broke down. The battery’s got plenty of life so I was certain there was a generator issue but the brushes look fine and the gen light glows bright without my touching the brushes at all. Here’s where it gets funny though. Even with the battery at full charge, if push the start button, nothing happens at all. No clicks or sounds or dimming of the headlight as I push the start. (The killswitch is off of course) But I noticed the neutral light is out when I turn the key on. I tried rolling the bike in 1st and 2nd and then popping it back into neutral but the neutral light still won’t illuminate. I’ve read that the ‘76 r90/6 MAY have a killswitch override that won’t allow the bike to start the bike if it isn’t in neutral or if the neutral light bulb is out or if any of the components associated with the neutral killswitch override is faulty. What are your thoughts?
Hi Glyn, I’m quite a long way from you, across country in East Anglia. But anyway, I don’t run a business fixing motorcycles, all the videos I do are either on my own bikes, or on ones that belong to family and friends. If you have a particular problem, I am happy to offer advice if I think I can. If you are looking for an independent technician, you could try the BMW Club magazine The Journal. There are a number of independents in there who advertise. One guy called Andrew Sexton who advertises there once did some machining work for me to a satisfactory standard. Hope that helps. Guy
Sir, have you had any experience with a high voltage overcharging condition? I have read to check for high resistance or an open in the regulator brown ground wire( the regulator was already replaced). Thank you.
leadfiremech Hi, it is always difficult to make a diagnosis at a distance. But if you are sure the regulator is not at fault, then I would start looking for an open circuit in the battery voltage sensing cable that goes to the regulator. This would prevent the regulator from doing its job.
Yes the space is quite confined. Nevertheless it is not too difficult, it may help to have the side panel off in order to push up from the underside once you have the battery lifted a little. Don’t forget to disconnect the battery breather pipe.
Can't say for sure, many BMWs do have them in the headlamp, others have them located elsewhere. For example, my GS PD has them under the left side panel. If you get hold of either a Haynes manual or a Clymer manual for your model you will be able to find out for sure. Another useful resource for airhead BMWs is Snowbum's website. It is a mine of useful information. Here is a link:bmwmotorcycletech.info/technical-articles-list.htm
Great video and information as ever! My R80/7 1979 is not charging. The charging light used to go out when the revs went up, but now the light stays on all of the time. What would you recommend I test first? and is there any particular order of things to test? Should I test the Diode board and Voltage regulator first? Any help would be really appreciated as I'm stuck on what to do next. Thanks
If you look at the current Haynes manual Mark on page 10.6, there is a good quick test there. That is a good place to start. Get back to me for further advice if you need it. Good luck, Guy
Thanks Guy, appreciate your help. Before reading your reply, I tried a test on the regulator. I removed and bridged the D+ blue wire to the DF blue/black wires together. Run the engine at approx 1500/2000 rpm and the charge lamp goes out. Did a metre reading and it was around 13.5 V. I'm guessing it should be 14V. Does that all sound correct? Regards Mark
So as i understand it, you got 13.5 at about 1500-2000 rpm with the blue and blue/black wire connected to each other. That is about right, if you take the revs higher the voltage should increase, but don't let it go past 15.5 - 16V. If this works, re connect the cables as they should be and replace the regulator. Note: if you are doing short distance, or stop, start in town a lot, you may like to consider a high output regulator. These are available from Motorworks, Motobins etc.
I am doing short distance, stop, start riding, so I'll look into a high output regulator, thanks for advise! I noticed that the wire connections to the regulator were quite dirty and corroded, so I put new crimp terminals on and the Gen light seems to be working ok so far!
Always good to check connections Mark. I cover and plug exposed electrical connectors with petroleum jelly (Vaseline). It works well, drastically slowing down oxidation, that inevitably leads to broken or poor connections. Especially if you ride year round.
Hi there. Great video. I was wondering if I could pick your brain as I am presently stumped. I have a 77 R100/7 which has been standing for 7 years. My generator light does not want to go out. I have replaced the whole charging system including: rota, stator, diode board and regular because no single replacement resolved the issue. As suggested in the manual I have tested the voltage between the B+/30 (disconnected) and the D- and now get about 14 to 15 volts. But at the battery terminals I get about 12.5 volts. Any ideas?
Hi, always difficult to diagnose faults remotely. Try removing the two cables at the brushes, then switch on the ignition. The gen light should be off, reconnecting the brush cables should relight the lamp. If the gen lamp stays on with the brush cables removed, there is likely a short somewhere between the lamp and the brush connection. If the lamp behaves as it should when the cables are disconnected (goes off), then it is likely there is a short in the rotor or slip rings. You can test the rotor with an ohm-meter like I do in the video, if the resistance is significantly lower than the manufacturers spec, the rotor should be replaced. Hope that helps.
Hi. The parts were getting tired and I needed to replace everything because every time I replace a part the voltage shot up. I probably didn't need to replace the diode board though. Finally resolved the issue. The D+ connector in the regulator connection block was not connecting and therefore nothing was getting to the back of the Diode board. Could not find a proper connection for the year of my bike(77), so ordered a "WIRING LOOM REGULATOR TO ALTERNATOR" for 70-76 from motobins. Had to adapt it and replaced the regulator connection block and wires D+, D- and DF to the diode board and rotor.
What about just one of the cables removed? If I remove the D+ the light stays on, DF removed the light turns off and both removed the light turns off. I am still trying to find the broken piece. Just got a new rotor and stator, and tried a new diode board as well. I am worried I fried the board somehow maybe with a bad ground? I had the cover off for all of this. Been scratching my head on this for a while now. Thanks.
Hi Jonny. I eventually resolved the problem by posting my issue on a BMW forum. They gave me a great step by step procedure to find the fault. See here: www.bmbikes.org.uk/Forum/viewtopic.php?f=15&t=23744
anotherrandomname2 Thanks for the comment, I don't always get to view, or perhaps have time to respond, but I'm glad to see this issue is now resolved.
Thank you for this extremely helpful video. I used it in changing the rotor in a '78 /7. At the same time, I changed the voltage regulator. However, I am still getting only 11.7 volts with the changing system. Does anyone have suggestions for other things that I can check to identify and solve the problem? Thanks.
Hi Emma, I am glad you found the video helpful, but sorry to learn you are still having problems. Does the charging system warning light come on when the ignition is switched on? If it does, does it go out when you start the engine? Make sure it fully extinguishes by checking in low light conditions (darkness). If you can still see a glimmer, it may be a faulty rectifier (diode board). Let me know how you get on.
I replaced the diode board and the brushes at the same time as I replaced the rotor and regulator. Now the warning light stays on at full intensity once the engine starts no matter what the engine r.p.m. This had been a problem before the bike died and I lost the warning light altogether, which led me to think that I had found the problem and answer with your video. I really appreciate your quick response but still wonder if you have any more suggestions.
Okay, as i understand it, your initial problem was that the warning lamp did not come on, so you replaced the rotor etc. Now the lamp comes on and stays on. Assuming my understanding is correct, then it may be the stator has become damaged. Locate the 3 phase winding terminals on the front of the stator (between 4 and 5 o'clock as you view the front of the alternator assy). Check the stator winding resistance between the three phase terminals in turn by placing ohm meter probes on any two terminals until you have tested the continuity of each of the three windings. The resistance between any pair of terminals should be about 6 ohms in all the tests. A significantly lower or higher reading points to a faulty stator. Also check the resistance between each terminal and the alternator body. This should give an open circuit or infinity reading. Any reading other than infinity is unacceptable. If the stator checks out okay, you need to re-test the regulator and rectifier. Remember, to always disconnect the battery when you are removing/replacing the rectifier as an accidental short will likely damage it beyond repair. Good luck!
The original problem was that the charging light was staying on most of the time, but then after the bike died on the road, the light would not come on at all. After I replaced the rotor, diode board, and regulator, the light came back on, and the bike seemed to run well, but the light was staying on at full intensity again. Because the bike has nearly 100,000 miles, and I would like to get it to be reliable again, I have replaced the stator and put in a new battery, but the generator light continues to be on at full intensity when the bike is running. Somehow I suspect that there may be a short in the system, but I am not sure how to find it or what other problems may be possible. Any suggestions?
With the engine stationary and ignition on, disconnect the D +/- wire at the alternator and the light should go out. If it doesn't try disconnecting the other brush cable (blue with black tracer). If it goes out this time, then there is a short somewhere between the two brush terminals; possibly rotor, or brush terminal connections. If with the two cables disconnected the lamp continues to stay lit, then it may be there is a short some where between the lamp and the DF brush terminal (cable blue with black tracer).
BMW electrical systems are the worst . It would be great if you told us the trick on making a puller bold out of a section of 6 mm metal . I'd do it but I forgot the proper length of metal .
Hello, I am writing türkiye.I have 83 model r65.right cylinder ignition is irregular.the failur spark plug.can you help me.what should I do.good and happy days
BA ÇA that’s quite a big question and you would need to describe the symptoms more specifically. If you are not getting any, or possibly irregular sparks at both sparking plugs, try checking there is consistent battery voltage at the supply side of the coil. If the supply is nonexistent or inconsistent, check through the electrical couplings and switches etc in the circuit up to that point for broken, dirty or intermittent connection(s). Use a voltmeter to help in your diagnosis. All measurements up to the coil should be within 0.5V of the measured battery voltage when the ignition is on.
BA ÇA Iridium plugs are okay, but not necessary in my opinion. If a new plug temporarily improves the engine running then you may have a problem with the coil. If it is the type that takes ht cables for both cylinders then it may have cracked, (these types of coil do have a reputation for developing cracks) this being the source of the misfire. Unless you have special coil testing equipment, the only way to be sure is to substitute one that is known to be working properly.
This guy is great. Very clear explanation, not too much information or too little. Straight forward and easy to understand. I even like the tone of his voice. Excellent.
Wonderful explanation! I just barely made it home a few hours ago (I ran the battery almost dry) and was dreading the inevitable confusion that erupts whenever I am faced with ohms, amps and volts. This video was a a lifesaver. I will head back to the shed with renewed confidence. Thank you so much for the help. Best wishes to all from Northern California. Stay well fellow Airheads!
Glad the video was of help. Keep well and all the best to you.
Great video. Although I am an electrician and mechanic I found the explanations, in lay-person terms, to be most helpful for those weekend and not so experienced troubleshooters. Excellent job. My son and I, who have worked on hundreds of motorcycles, are going to be troubleshooting the charging system on a recently gifted R65 this morning so this crash course will come in handy even for us.
For years I've known this to be an easy problem to diagnose and to repair, but have yet to see it done in such basic, layman terms that the mere mortal can do ! No high tech terminology no stream of curse words for the sake of cursing. Just a calm gentleman showing a novice how to do it as of we were there one on one in his shop with a cuppa Rosie and perhaps and old dog laying by the heater, brilliant and many thanks from Calif !
If you ever get my way, I have an R75/6 you may use to tour the sights !
What a lovely compliment. Thank you!
Watched this video...All the wiring checks I did pointed to the rotor needing replacing so I got a new rotor from Motorworks...Who I must add were really helpful when I visited them...So checked a few of the connections which all seemed to be fine...After the rotor was installed I checked on the off chance to see if there was a spark...and there was...So I fired up the old girl and she responded straight away...So now I have her running...If an open circuit rotor was an issue I am a bit confused as to what was wrong with the non-sparking issue but at least she runs now...Thanks again for all your instruction videos on these beautiful bikes...They are so helpful!
I’m pleased to hear that you have got the issues sorted. For sure an open circuit rotor will not affect the ignition system so long as the battery has sufficient charge. But the main thing is that your bike is now working. Thanks for the kind comments. All the best for the future.
Thanks a lot for a very clear, down-to-earth, no-nonsense video! And for not having any fancy music, logos, or intros in it, either. So, make more of these, please! Airhead electrics can be a bit mysterious to some of us, so this is really useful, at least to me; my bike is a 1983 R100RS, but the electrics are basically the same.
;-)
Glad it was of some help. I’m expecting to be doing some more work on Tim’s R80/7 in December. Hope to make a video of that.
Excellent, thanks! :-)
Thank you for the video. I'm currently rebuilding a R65 and only got a charge of 11.7 volts. I'll be using this method to check the rotor arm now as i have just checked the diode board and that seems to be working.
+Trikerbloke Turns out it was the regulator on mine. I made a quick video to show how I diagnosed it and put a link in to this video for the rotor. Hope thats alright.
4 years later and I'm here again...Sorry to be a pain again...R100GS (1990)...Haven't run the bike since last year and bought a new battery yesterday...Issues with the charging again...Battery light stays on (but dim) during running...I checked the battery posts while the bike was running but the voltage does not go up...I checked the rotor and that was new 4 years ago and is ok using your test...The actual alternator came off with a little persuasion but I noticed that the wiring mesh on the back is slightly loose although not too bad and not unconnected...I did run the multimeter on the 0-200K (same as for the rotor) and used it to see if the wiring on the actual alternator was ok and I got a reading from the red and blue but not the white one...One thing I did notice is that my wiring on the rotor is different from the one in the video - the red and blue wires are the other way around on mine...I'm hoping I didn't get them mixed up when I did this 4 years ago (I dont think so) ...Anyway...Any ideas...Thank you for any help
The battery was actually dry when I checked it this year which was a bit of a shock as it was a new battery last year...I've been a carer since xmas for my step-father this year up to a month ago, hence no biking
There's a sharp bend of the coil where it connects to the slip ring. There was a remanufacturing supplier who rewinds them taking out the bend making the rotor more reliable
AThank you for a very well presented and structured account of how to do the magic. I can't wait to get the old girl back home and get her sorted. Keep up the good work. Dave Holden.
Splendid lecture. I feel very comfortable now, at troubleshooting my R100 charging issues in the future.
I have done all checks from this video. Easy to understand and most importantly clear vocal. I had narrowed down the fault from the brown wire into the bulb, but cant find the reason why the bulb doesnt go off during high rpm. Im using a 450watts Endura with its’ upgraded diode board btw.
Is this the alternator kit with a permanent magnet rotor?
Thanks for the video! My gen light was going intermittently on my /5 so I used your process to troubleshoot it. Turns out my brush wires had come unsoldered and were just rattling around loosely in their holes. Got them soldered up and pulling 13.6v at 3500 rpm. I'm still going to eventually upgrade to the EnDuraLast 450w system, but this will delay that process for a while now.
Thanks ive just bought a bmw r75 /5 with charging issues so this vid helps
Thanks for the informative video, I was looking to see what the rotor removal tool looked like.
One thing I failed to notice ( I may have missed it) is that you made no mention of the slip rings being glazed-over. This would also give an open-circuit reading, but could be rectified with fine wet/dry paper to clean them, and not need a replacement rotor. Best regards Iain
Thanks for the comment Iain.
I usually clean slip rings and commutators with an abrasive 'nylon' pot scourer followed with a wipe over with an alcohol soaked rag to degrease. Which is what I seem to recall doing on this occasion. I use this method instead of abrasive paper to reduce the chance of 'grit' off the paper becoming embedded in the slip ring. Alternatively, I have used a commercially available switch cleaner.
Thanks a lot my friend, from Mallorca all the best to you.
Thanks for the video. Had the battery on my 1990 R100GS go flat. Battery recharged OK. Used your process to check the problem and turned out to be the rotor open circuit. Luckily had a spare rotor and extractor bolt to hand and it took me 80 minutes work to analyse and replace. Super. Now I just need a video to explain the reason for having a warning light that fails to indicate a lack of charging, when the alternator wiring fails.
I'm pleased you found the video helpful. To get around the design weakness you in this system, you could always fit a voltmeter; if my memory serves correctly, BMW did offer a voltmeter as an accessory to fit the early GSs. Alternatively you could fit a battery status monitor, available from AO services: www.aoservices.co.uk/index.htm I have had one for years on my GS PD, it works very well.
Exce!lent review.I am now able to go and check my charging issues tomorrow. Thanks for taking the time to help others.
Hi posted an initial comment on general video, positive of course, just put the old girl back together. Shifting this stator was a bit of a challenge, until I compared it with the "new" one, I found a long jemmy with a "shallow" end angle and used this to get the whole lot moving. She fired up a treat. Only thing which have would made the vid A*+ would have been to linger a little on the three cable re-connect with better lighting. But first class effort, and if I hadn't been a numpty I would have remembered the order for myself. Keep up the good work.
I wish I had seen this two days ago, would have saved a lot of frustration and swearing.....exact same problem as you had...thanks!
This video is exceptional as well as the mechanic! Clear and concise, easy to understand and to follow. I have liked and subscribed and now I need to follow up on your other videos. You have my sincere thanks for your time and effort for sharing your knowledge and skill with us!
Thanks for your kind comment. I think I hit the spot with this one. Lots of folk seem to like it.
A great video, thanks for a clear demonstration throwing some light on what was a murky subject for me, many thanks
Thanks, it is kind of you to say so. Yes there are more coming soon.
Sorry for the delay in reply, I'm still getting to grips with RUclips
Thanks so much for this video...I am a whiz with mechanics but draw a total blank with electrics so this vid is perfect as a step by step walkthrough for folk like me...Thanks you
You are very welcome.
Thanks man.....a great step by step process explained in detail.
Thanks so much for the link guy! I did some 2 year motorcicle technics eveningsxhool, long ago,your videos refresh mybasics , thnks forthat!
Thanks for posting this clip. I needed to know how to R&R the rotor and this showed how very well.
Learning quick, I have the EnDuroLast 450w works great so far. Also found bill for EME Endurolast digital electronic ignition. EME starter as well.
Thanks...very useful information for all airhead enthusiasts out there!!!
Thank you so much for this video! Probably cut my research time by 50 hours XD
Thank you for the video , I just picked up 1976 BMW R90/6 it does not run but Im working on that .....this will help
Glad the video is of help to you. Good luck with the new project.
I've had an R90/6 for ~25 years. It's been very reliable and it's a sweet-riding machine. It's not nearly as fast as my R1200... but still nice for an old-timer.
I have a problem of the gen light on all the time and not charging battery.
light off when ignition off.
rotor has continuity with brushes not touching and the correct ohms reading.
I have revved to over 3000rpm and light still on and no charge.
1981 r100rs
Any suggestions ?
Brushes are not worn and I did not replace them recently so, I excluded any issues with mounting them back
Guy, thanks so much, I will keep watching your videos and follow your advice. Many Thanks Glyn.
Thanks for a helpful video. The screw used for pulling out the rotar is there a name for it?
hello thank's for video , it's so exlicit , please a l have a question , what 's the signification when the lamp of charging not on ???
So the charging lamp indicates the balance of electrical output of the alternator with the battery. With the ignition switched on without the engine running electrical current flows from the battery through the ignition switch to the lamp and then the circuit continues through the rotor and back to the negative terminal via the motorcycle engine casing and frame. Under normal circumstances when the engine is running, the rotor develops a voltage in it’s windings that opposes the flow to the bulb from the battery and when the opposing voltage is high enough the lamp is extinguished: that is the voltage in each direction is balanced. This point at which this opposing voltage balances is also the point where the alternator output from the stator becomes greater than battery nominal voltage and hence the battery will be charging. If a fault develops, for example the stator stops working then the system will be out of balance and the lamp will come on, indicating that the battery is not charging.
Hey Moto! guess what? I found a 72 r60/5 in a dusty garage stored since '82 and 40k miles on it. silver vrs. Got it from an ex pat for about 1400 quid! light drop damage but I have it all working now and licensed. I will make vid soon, may need a starter relay and or starter button turn signal switch. I have the bare relay wrapped in rubber hanging below tank so I can trip the contact to start it when cold. No signal in relay when manually ground brown single wire. Fast bike! I also got the rt up to about 223kph smooth to 200 bit sketchy there after, rear rotor was warped new one fixed issues. found out it was police guys bike plenty of hi-pro motor work in it.
441rider wow! They are quite rare nowadays and £1400 is good value. Look forward to seeing a video.
I guess temperatures are starting to drop now where you are. I’ll be leaving soon for what will probably be my last blast of the year soon. Off to Portugal to see my buddy for 2 or 3 weeks. I’ll try to post some video of the trip.
Meanwhile I’ve just put up one about a home made emergency gear shift tool to use in case the selector pawl spring breaks on your 5 speed transmission (it’s known to happen).
Ahh the wire do-hicky to lift it into a gear. I will check out the vid. The r60/5 parts in good nick are few and far between and the headlight pin ignition board needs a good after market option. I want to keep it stock but it will be my city bike until I get the 441 bored and in the new frame. cold rain and short days already but a few sunny warm riding days still with the fall colours.
I have the eme upgrade and both my friend and myself have identical R100 pd with same problem: not charging. Any ideas before I start trashing another stator? Fred
thank you for video i have similar pb and i am gonna sort this out but you missed to say in the begining it could be also a faulty voltage regulator for this symptom i mean thegen lamp don t turn on
great video... i got the exact opposite problem i just put on a new charging system stator, rotor , voltage regulator .brushes and now my battery warning light is staying on anything i should trouble check ?
Great explanation, thanks
Excellent video - many thanks!
I have a few old airheads I am rebuilding, and they both seem to not charge very well. I am only getting about 12.9V at idle and about 13.2V at 2000 RPM on a healthy Shorai Battery. The rotor is only showing about 1.5-2.0 Ohms, (But that is not pulled off the bike - not sure that matters) Is that enough to give you a weak charge. The brushes seem fine but will replace those too. Thanks in advance.
To check the charge rate, first switch on the headlamp for 5 min without the engine running, then connect a multimeter set on the 0 - 20 volt scale to the battery. Leave the lights on and start the engine, observe the meter it should read between 13.5 and 14.5 V and then start to fall back as the battery charges up.
Early airheads had slightly lower power generators. If you check in a workshop manual you will find the values correct for your generator. If the rotor resistance is low replace it. Resistance should be checked with the brushes not in contact with the slip rings. Slip a piece of paper between the brushes and ring when you check. May also be worth checking the regulator and rectifier next.
Hi, I have the opposite problem. When my ignition key is ON, the GEN lamp goes ON brightly, but it only fades a bit when the engine is revv'd up. I tested the diode board, the rotor and the rectifier and all are good. What else could it be the cause of the low charging?
Hi, sorry to learn that you are having trouble. You say that you have tested the diode board and the rectifier, but they are the same thing. Did you mean the voltage regulator? If you are sure that the components you have tested are functioning properly, then the only thing left is the stator. It is unusual for these to fail, but if they do they can either fail because one or more of the phase circuits has either got open circuit, or there is a short. Testing with an ohm meter should show either fault up. Good luck.
@@motophoenix5951 yes, sorry, I meant the regulator and the rectifier. What I did is replace the existing one with spare units that are good and that did not solve the problem. I made the measurements on the rotor and I have good readings.
Concerning the stator, should I take measurements when mounted or dismounted and I guess at the 3 terminals to check if the stator is open or close, right?
My R100GS doesn't have an ignition spark...I haven't run the bike for a few years...The only light I have on the dash at the mo with a new battery is the green neutral light...The engine turns over but no spark....I know that the alternator wasn't charging when I last ran the bike...Could it be that the rotor on its own is at fault?...
No a faulty rotor will not affect the ignition system. If the bike has been laid up, it is probably a high resistance (dirt, oxidation) at a connection somewhere along the ignition circuit. I suggest you use a multi meter set at 0-20V dc, or use a12V bulb to probe live connections. Connect the black lead of the meter, or one side of the bulb to a good earth and probe connections with the other. If voltage drops or the bulb is dim/out the connection will need cleaning. If as you suggest, there is a supply to the ignition switch, start there and work your way along. Hope that helps.
Big thank you for your help MP...I'll try that...Plenty of time on my hands at the mo...Thanks
Good video, thank you sir. From Florence, Texas, USA
Thank you. It is always great to hear from folks near by or far away.
hello sir, very interesting vid, tnk u so much!! ;) , i have the same problem with my R80RT and i have two questions:
*you've disconnected the battery earth cable to open the cover, then you've reconnected it, Do u keep it that way and do all the next steps?
*Do i have to change the rotor itself or the wire only?
thank you again and hve a gd day!
Amine Makhlouf Hello, I only disconnect the battery to remove or refit the cover, since it is very easy to cause a short circuit by touching the cover on the rectifier (diode board), mounted above the alternator. This may result in overheating and damage to the electrical components. So, yes, reconnect the lead to carry out the next steps.
If you can I would recommend replacing the rotor. However, you may be able to find an electrical specialist nearby who can rewind the old one. I have had this done in the past, but with limited success, since the rewound rotor did not last as long as the original Bosch item.
Good luck with your repair.
great video and useful tips as well!I have a 1982 R100T which has a charging problem...I will leave the battery on a trickle charger overnight which will be fine for a few days but riding around will eventually drain the battery.battery is almost new from BMW, I have tested the rotor for resistance and it came back at 3.8 ohms, I shorted the regulator to see if it is the problem, once done I couldonly get 12V at around 3000rpm, i was under the impression that this procedure would give full output to the alternator..at least up to 14v or so but no luck even reving the engine it was stuck at 12v. once the plug was back in I got around 8V and generator light was on!!!any input you can share?thanks,Terry
Hi Terry. The resistance between slip rings on the rotor looks okay. Not sure what you did when you say you shorted the regulator, but you should have removed the regulator and bridged the D+ (blue wire) to the DF (blue/black wire) on the socket. Run the engine between 1000 and 2000 rpm briefly. If the charge lamp goes out, then the regulator is likely at fault. If not then you will need to look elsewhere, possibly the stator. You can check the stator winding resistance between phases; should be about 0.62 ohms. Between phases and earth should be open. Good luck.
Hello, thanks for the video really helpful for novice like me. My R100 is no longer charging, i check everything as described in your video and could not find any issue. I removed the rectifier and shunt the black and blue cable, then started the bike and battery was charging. I assumed that the rectifier was bad and bought a new one. After installing it, all was good, battery was charging. 3 weeks later same problem, battery not charging. It seems that the rectifier is again bad which i cannot really understand. Any idea why rectifier will go bad so quickly ?
Any help would be appreciated
Hi, sorry to learn that you are having troubles with your charging system.
I am a little confused by your terminology. You speak of replacing the rectifier (aka the diode board), but the test you have carried out relates to checking a possibly faulty regulator. So I assume you were talking about the regulator.
Anyway, can we establish the circumstances of your non functioning charging system. Does the generator warning lamp stay on all the time? Or does the warning lamp not come on when the engine is stationary with the ignition on? Or is the warning light on all the time, but glowing very dimly; check this in low light conditions to be sure.
Regulators do not often go wrong and from your initial description I suspect you may have a bad connection. Check for worn alternator brushes and/or dirty slip rings. Lift off the brush springs and pull out the brushes to establish that they are not worn out; minimum length 8mm. Inspect cable connections to make sure they are not generating a high resistance because they are dirty.
When you have made these checks, get back to me.
Regards...
Moto Phoenix hi, apologize for replying so late to you, I was on vacation. You are indeed correct, I meant the regulator located under the tank.
First I have to say that the bike has been modified by the previous owner and that it does no longer has the original dashboard. A tachometer including LED’s has been fitted.
The light on the dash glows as soon as I turn the key and stays on all the time, also while driving. I have performed following check:
- battery voltage 12.4V
- rotor front brush to rear brush, 3.9ohm, checked at the brush surface like in your video
- rotor front brush to casing, nothing
- rotor rear brush to casing, nothing
- stator 0.6 ohm between each phase
- stator, checking each phase to casing, nothing
- Df cable (blue black) 0.3 ohm (stator side to regulator connector)
- D- cable (braun) 0.5 ohm (stator side to regulator connector)
- Y cable 0.3 ohm
- D- connector on stator to rear brush 0.6 ohm
- D- connector to front brush, nothing
- Df connector on stator to front brush 0.4 ohm
- Df connector to rear brush, nothing
- ignition on and Df cable on stator side unplugged, dashboard light glows (I would have expected it to not glow)
- ignition on and D- cable on stator side unplugged, dashboard light glows (I would have expected it to not glow)
- regulator connector unplugged and ignition on, dashboard lamp does not glow
- regulator connector unplugged and blue & blue/black bridged, ignition on, dashboard lamp glows
- bike started with blue & blue/black connector on regulator connector bridged, battery voltage raising when accelerating
- cleaned as best as possible the regulator connector and replugged to regulator, bike started, battery is charging and regulating to 13.9/14.2V
I must say that I am a bit puzzled because I did unplugged the regulator connector in the past several times and it made no differences. What is more surprising is that I had the same issue 3 months ago and back then, I cleaned everything.
Do you know how to remove each cable from the plastic connector so I can inspect each cable and cable shoe? I tried to push from the top but did not manage to get the cable out.
Thanks again, Manuel
This was a fantastic video thank you... guess I need a new rotor.
on another note... do you have a video about replacing or rebuilding the master cylinder on a 1976 R90/6? my bike has been sitting for a year and in diagnosis the rotor issue I noticed there is quite a leak in the master cylinder.
thoughts.
Thank you
+John Doe Thanks, I'm pleased the video helped. Unfortunately I do not have a video on how to repair a master cylinder. Some time in the future possibly. You could try Chris Harris for that. Here is a link: ruclips.net/channel/UCRZEzmVmi88hqnVKe7d-wIg
So if I did these tests and my Gen light never turned on, does that mean my Gen light is out? I was riding on the freeway and my 84 R100RS died as if someone hit the kill switch. Towed the bike home and tested the battery and it was at 10.59 and Gen light never turned on. Charged battery to 13.4 volts, completed tests in this video still no Gen light. Thanks in advance.
So I tested the Gen light bulb and the bulb was fine. Any other tips? I tried everything in the video and still no Gen light.
@@BIGGZ46if the bulb works when you test it independently and you have done the test I showed in the video, the next thing to do is to test if there is there a supply to the bulb? Use a voltmeter to test the live supply to the bulb when the ignition switch is on.
A very useful video! Thanks!
Hi, thanks for your video, it is very professional and educative. I was wondering if you knew what yo do when the GEN LIGHT is always ON? I have done every steps you showed on this video, I read a resistance of 2.7 ohms on stator, but very different with the brushes ( cannot remember well but around 67 ohms)>
I changed the voltage regulator, and I also had a burnt red wire ( i think it is #86) going from the starter relay on the left side of the tank to the blinkers clip ( black clip with 6 wires).
Would you know by any chance if there is a way of testing the relay with a multimeter? ( I will buy one whatever happens but for the future if it happens again)
And also, should I replace that wire, knowing that I do not run any blinkers ( post 1985 motorcycle in New York state do not have to have blinkers).
I really appreciate your videos, they are very helpful, and are much more easier to understand than reading a book.
Cheers,
Robin
+Robin Zeitoun To test the most common type of relay, connect each lead of your multi-meter to terminals 87 and 30 (doesn't matter which way round), then set the meter to the 0 - 200 ohm scale. The ohm meter should read open circuit, i. e. infinity. Leave the meter connected to terminals 87 and 30, then connect terminals 85 and 86 to the battery + and - terminals (doesn't matter which way round). You may then hear a click and see a very low value (almost 0) on the meter. When you break the battery circuit the meter should read infinity again.
If the cable attached to 86 is burnt on your starter relay, replace the damaged piece of cable. Investigate and try to find out why it is burnt. Seems to me there may be a short. You do not mention which model you have but from memory I seem to recall 86 is live when the starter button is pressed and 85 goes to earth possibly via the clutch and/or side stand isolator. But you should check on a wiring diagram
Regarding the Alternator, first you will need to have access to data about the alternator for the model of airhead you are working on. I suggest you get hold of a copy of the manual for BMW 2-valve twins 70 to 96, published by Haynes. At the beginning of chapter 10 you will find under the section headed Specifications the data you require in order to make comparisons with your own readings. Section 6 in the aforementioned chapter will guide you through a number of tests you can perform to help diagnose your problem.
It is usually difficult to make a diagnosis of electrical faults from a distance and I think your best and quickest route lies with the use of your meter and a logical sequence of investigation as on offer from the Haynes manual.
Hope that helps.
+Moto Phoenix Thanks a lot for your quick reply.
I completely forgot to mention the year and model.. It s a 1984 R100 RT. About 60K miles on it.
I found out why the red wire got burnt :
Not long ago I disconnected that connector ( it was attached to blinkers, clock, and voltmeter), as I am turning the bike into a cafe racer and did not need any of the instruments nor the blinkers, although I reckon some water introduced itself in the connector that I left kind of hanging around, and shorted it...
I am lucky it happened in front of me and was able to trace it to that wire that was useless at the time.
As for the starter relay, I ended up buying a new one. It was probably the original one from 1984 by the look of it... Although I will get a Haynes manual, surely it will come in handy!
Thanks again for your help, I will let you know how I go.
Cheers!
You are welcome Robin Zeitoun and I look forward to hearing from you again.
+Moto Phoenix I ended up getting the clymer to find out what was wrong. I found the book very vague unfortunately, but I was able to identify very quickly that the diode board was faulty ( also thanks to you using the diode board testing videos you made). One of the diode burnt out ( Still trying to figure out why so it doesnt happen again, although I m thinking the battery is a bit old and also used a dry cell one a few times, which would have damaged it).
I have another question for you ; I read on a few forums that the rubber mounts were not the greatest to keep on, so ended up buying the metal one for euro moto electric. BUT, to access the inner nuts, I might have to remove the starter motor. Would there be any other easier/quicker way that would not involved removing anything. I am pretty switched and capable of doing all that but from experience, if something works well and does not need to be moved, I would rather leave it where it is.
Thanks again!
Cheers,
Robin
Hi Robin, diodes burn out occasionally. But it may be worth checking for a bad connection from the soldered joint melting, caused by the heating effect of the rectification process. I have had this happen to a couple of diodes on my 400 W generator set-up. I re-soldered the joint each time with old-fashioned plumber's solder (higher melting point), which appears to cure the issue.
Personally, I am not adverse to rubber mounts, but they do fail from time to time. They are very awkward to change and I did fit the solid ones that came with my 400 W kit. I have managed successfully in the past by using a 1/4 drive socket that incorporated a u/j, but even then it's a fiddle. Or you could try holding the nut with needle nose pliers or magnet whilst you screw the mount onto the nut, then finish with a socket or spanner. Good luck
So if I push on the brushes (to connect to the slip ring) and the light turns on then the brushes aren’t the issue?
If you have to push the brushes onto the slip-ring to make the warning lamp illuminate, then it would seem to me that there is a poor connection between the brush and the slip-ring. The brush(es) may be excessively worn, the slip-rings may require cleaning or the brush spring may be weak/broken.
Moto Phoenix
Thank you so much for the response.
I’ve a puzzle I’m working on and I sure wish I had the expertise you do.
I have a ‘76 r90/6. The gen light has always flickered on and off for the 6 years that I’ve owned it but it’s never left me stranded. Then, one night, it started to die as if it wasn’t getting enough fuel. (It had plenty of fuel) So I cranked it back up (the electric start struggled but it finally started) and it kept wanting to stall unless I revved the engine at high Rpms. I eventually had to stop at a red light and the bike stalled as soon as the RPMs dropped. The battery appeared to be so weak that it would even click when I pushed the start button. So I push started it and was able to limp it down the road a bit without the headlight on.
The battery was just purchased that month and was tested after the bike broke down. The battery’s got plenty of life so I was certain there was a generator issue but the brushes look fine and the gen light glows bright without my touching the brushes at all.
Here’s where it gets funny though.
Even with the battery at full charge, if push the start button, nothing happens at all. No clicks or sounds or dimming of the headlight as I push the start. (The killswitch is off of course)
But I noticed the neutral light is out when I turn the key on. I tried rolling the bike in 1st and 2nd and then popping it back into neutral but the neutral light still won’t illuminate.
I’ve read that the ‘76 r90/6 MAY have a killswitch override that won’t allow the bike to start the bike if it isn’t in neutral or if the neutral light bulb is out or if any of the components associated with the neutral killswitch override is faulty.
What are your thoughts?
Good Morning Guy; where are you based to. I live in Cornwall and I am looking for a good mechanic to do some work On my R80/7.Thanks Glyn.
Hi Glyn, I’m quite a long way from you, across country in East Anglia. But anyway, I don’t run a business fixing motorcycles, all the videos I do are either on my own bikes, or on ones that belong to family and friends. If you have a particular problem, I am happy to offer advice if I think I can.
If you are looking for an independent technician, you could try the BMW Club magazine The Journal. There are a number of independents in there who advertise. One guy called Andrew Sexton who advertises there once did some machining work for me to a satisfactory standard.
Hope that helps. Guy
Sir, have you had any experience with a high voltage overcharging condition? I have read to check for high resistance or an open in the regulator brown ground wire( the regulator was already replaced). Thank you.
leadfiremech Hi, it is always difficult to make a diagnosis at a distance. But if you are sure the regulator is not at fault, then I would start looking for an open circuit in the battery voltage sensing cable that goes to the regulator. This would prevent the regulator from doing its job.
Moto Phoenix Thank you sir
Hi there have you any tips on changing the battery on these bikes it looks a bit awkward to me
Yes the space is quite confined. Nevertheless it is not too difficult, it may help to have the side panel off in order to push up from the underside once you have the battery lifted a little. Don’t forget to disconnect the battery breather pipe.
@@motophoenix5951 thanks for that
Good info!...thx...do we have some or all? Fuses in the headlight? On rs 100 Year1979?
Can't say for sure, many BMWs do have them in the headlamp, others have them located elsewhere. For example, my GS PD has them under the left side panel.
If you get hold of either a Haynes manual or a Clymer manual for your model you will be able to find out for sure.
Another useful resource for airhead BMWs is Snowbum's website. It is a mine of useful information. Here is a link:bmwmotorcycletech.info/technical-articles-list.htm
TY so much for this!!!
Great video and information as ever!
My R80/7 1979 is not charging. The charging light used to go out when the revs went up, but now the light stays on all of the time.
What would you recommend I test first? and is there any particular order of things to test?
Should I test the Diode board and Voltage regulator first?
Any help would be really appreciated as I'm stuck on what to do next.
Thanks
If you look at the current Haynes manual Mark on page 10.6, there is a good quick test there. That is a good place to start. Get back to me for further advice if you need it. Good luck, Guy
Thanks Guy, appreciate your help.
Before reading your reply, I tried a test on the regulator. I removed and bridged the D+ blue wire to the DF blue/black wires together. Run the engine at approx 1500/2000 rpm and the charge lamp goes out.
Did a metre reading and it was around 13.5 V. I'm guessing it should be 14V.
Does that all sound correct?
Regards
Mark
So as i understand it, you got 13.5 at about 1500-2000 rpm with the blue and blue/black wire connected to each other. That is about right, if you take the revs higher the voltage should increase, but don't let it go past 15.5 - 16V. If this works, re connect the cables as they should be and replace the regulator. Note: if you are doing short distance, or stop, start in town a lot, you may like to consider a high output regulator. These are available from Motorworks, Motobins etc.
I am doing short distance, stop, start riding, so I'll look into a high output regulator, thanks for advise!
I noticed that the wire connections to the regulator were quite dirty and corroded, so I put new crimp terminals on and the Gen light seems to be working ok so far!
Always good to check connections Mark. I cover and plug exposed electrical connectors with petroleum jelly (Vaseline). It works well, drastically slowing down oxidation, that inevitably leads to broken or poor connections. Especially if you ride year round.
Hi there. Great video. I was wondering if I could pick your brain as I am presently stumped. I have a 77 R100/7 which has been standing for 7 years. My generator light does not want to go out. I have replaced the whole charging system including: rota, stator, diode board and regular because no single replacement resolved the issue. As suggested in the manual I have tested the voltage between the B+/30 (disconnected) and the D- and now get about 14 to 15 volts. But at the battery terminals I get about 12.5 volts. Any ideas?
Hi, always difficult to diagnose faults remotely. Try removing the two cables at the brushes, then switch on the ignition. The gen light should be off, reconnecting the brush cables should relight the lamp. If the gen lamp stays on with the brush cables removed, there is likely a short somewhere between the lamp and the brush connection. If the lamp behaves as it should when the cables are disconnected (goes off), then it is likely there is a short in the rotor or slip rings. You can test the rotor with an ohm-meter like I do in the video, if the resistance is significantly lower than the manufacturers spec, the rotor should be replaced. Hope that helps.
Hi. The parts were getting tired and I needed to replace everything because every time I replace a part the voltage shot up. I probably didn't need to replace the diode board though. Finally resolved the issue. The D+ connector in the regulator connection block was not connecting and therefore nothing was getting to the back of the Diode board.
Could not find a proper connection for the year of my bike(77), so ordered a "WIRING LOOM REGULATOR TO ALTERNATOR" for 70-76 from motobins. Had to adapt it and replaced the regulator connection block and wires D+, D- and DF to the diode board and rotor.
What about just one of the cables removed? If I remove the D+ the light stays on, DF removed the light turns off and both removed the light turns off. I am still trying to find the broken piece. Just got a new rotor and stator, and tried a new diode board as well. I am worried I fried the board somehow maybe with a bad ground? I had the cover off for all of this. Been scratching my head on this for a while now. Thanks.
Hi Jonny. I eventually resolved the problem by posting my issue on a BMW forum. They gave me a great step by step procedure to find the fault. See here: www.bmbikes.org.uk/Forum/viewtopic.php?f=15&t=23744
anotherrandomname2 Thanks for the comment, I don't always get to view, or perhaps have time to respond, but I'm glad to see this issue is now resolved.
Thank you for this extremely helpful video. I used it in changing the rotor in a '78 /7. At the same time, I changed the voltage regulator. However, I am still getting only 11.7 volts with the changing system. Does anyone have suggestions for other things that I can check to identify and solve the problem?
Thanks.
Hi Emma, I am glad you found the video helpful, but sorry to learn you are still having problems. Does the charging system warning light come on when the ignition is switched on? If it does, does it go out when you start the engine? Make sure it fully extinguishes by checking in low light conditions (darkness). If you can still see a glimmer, it may be a faulty rectifier (diode board). Let me know how you get on.
I replaced the diode board and the brushes at the same time as I replaced the rotor and regulator. Now the warning light stays on at full intensity once the engine starts no matter what the engine r.p.m. This had been a problem before the bike died and I lost the warning light altogether, which led me to think that I had found the problem and answer with your video. I really appreciate your quick response but still wonder if you have any more suggestions.
Okay, as i understand it, your initial problem was that the warning lamp did not come on, so you replaced the rotor etc. Now the lamp comes on and stays on. Assuming my understanding is correct, then it may be the stator has become damaged. Locate the 3 phase winding terminals on the front of the stator (between 4 and 5 o'clock as you view the front of the alternator assy). Check the stator winding resistance between the three phase terminals in turn by placing ohm meter probes on any two terminals until you have tested the continuity of each of the three windings. The resistance between any pair of terminals should be about 6 ohms in all the tests. A significantly lower or higher reading points to a faulty stator. Also check the resistance between each terminal and the alternator body. This should give an open circuit or infinity reading. Any reading other than infinity is unacceptable. If the stator checks out okay, you need to re-test the regulator and rectifier. Remember, to always disconnect the battery when you are removing/replacing the rectifier as an accidental short will likely damage it beyond repair. Good luck!
The original problem was that the charging light was staying on most of the time, but then after the bike died on the road, the light would not come on at all. After I replaced the rotor, diode board, and regulator, the light came back on, and the bike seemed to run well, but the light was staying on at full intensity again. Because the bike has nearly 100,000 miles, and I would like to get it to be reliable again, I have replaced the stator and put in a new battery, but the generator light continues to be on at full intensity when the bike is running. Somehow I suspect that there may be a short in the system, but I am not sure how to find it or what other problems may be possible. Any suggestions?
With the engine stationary and ignition on, disconnect the D +/- wire at the alternator and the light should go out. If it doesn't try disconnecting the other brush cable (blue with black tracer). If it goes out this time, then there is a short somewhere between the two brush terminals; possibly rotor, or brush terminal connections. If with the two cables disconnected the lamp continues to stay lit, then it may be there is a short some where between the lamp and the DF brush terminal (cable blue with black tracer).
Excellent! Thank You!
BMW electrical systems are the worst . It would be great if you told us the trick on making a puller bold out of a section of 6 mm metal . I'd do it but I forgot the proper length of metal .
Hello, I am writing türkiye.I have 83 model r65.right cylinder ignition is irregular.the failur spark plug.can you help me.what should I do.good and happy days
BA ÇA that’s quite a big question and you would need to describe the symptoms more specifically.
If you are not getting any, or possibly irregular sparks at both sparking plugs, try checking there is consistent battery voltage at the supply side of the coil. If the supply is nonexistent or inconsistent, check through the electrical couplings and switches etc in the circuit up to that point for broken, dirty or intermittent connection(s). Use a voltmeter to help in your diagnosis. All measurements up to the coil should be within 0.5V of the measured battery voltage when the ignition is on.
@@motophoenix5951 than you for your information.do you advise using iridium based spark plug?
By the time spark plug changed especially the right one the problem is temporally solvet.
BA ÇA Iridium plugs are okay, but not necessary in my opinion.
If a new plug temporarily improves the engine running then you may have a problem with the coil. If it is the type that takes ht cables for both cylinders then it may have cracked, (these types of coil do have a reputation for developing cracks) this being the source of the misfire. Unless you have special coil testing equipment, the only way to be sure is to substitute one that is known to be working properly.
@@motophoenix5951 First of all, thank you for your interest. The ignition coil of the motorcycle has a crack.
Thnx useful vid!
Great video could do with you around stoke
would this be the same as a r100gs?
Yes, the charging system works the same way.
love your vids!! thanks!
Thanks for the kind comment.
Every car alternator has a cooling fan to prevent burning uo the windings.
But BMW airheads have no such fan and don't even have a cooling air flow.
Merci !
hi guys
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