You honestly have the most through marine repair videos on RUclips. Made your DVA adapter and used it a lot this summer to replace CDI units. Keep up the good work, always intrigued.
WOW!! And here I thought all the spark plug did was deliver the spark, so much here that I did not know and very important stuff, your second career could very well be that of a teacher, I've always said that there are many experts in life but very few who can explain a subject in such a way that it sticks to you like glue, your one of these people, thank you
@@DangarMarine absolutely! Curious if you could take a peek at the last video I uploaded, just to see if that’s how my carb should be functioning. Sorry to bother you! -Gray
Dude can I get college credits! Wow blown away how informative and simple you break it down. You should make a multiple choice quiz after each video ✌️
Great tutorial on spark plugs Stu. Especially the part about running the motor at speed and then pulling the plug right away to examine it. Very good information!
I'll just say I've been watching your videos for a long time and have fixed many outboards because of you saving me $1000s in mechanic fees. Thank you for that. I would like to through a suggestion for a video dealing with adjustment of loose steering on cables. Some time would be nice again thanks for your sharing of knowledge!
Wow..had no idea it mattered where the tip of the spark plug was facing inside the head!! Man you have made my day..you have taught me more in your videos than i have ever heard about before.. Pls..write some books for people who want to do things correctly.. Thanks again ..
Another winner, Stu. Thanks very much. Always thought those gapless plugs made a lot of sense. Several Mercury 2 strokes we had in the Eighties specced them.
Have a look in the Johnson 50 - they are gapless as spec'd. Also aircraft engines typically use gapless or face firing plugs - sometimes for piston clearance reasons, usually for the reliability factor. Its a bit hard to stop and check whats wrong at 10,000ft!
just caught up with this video Stu very informative as usual 1 uncommon failure I want to share is when the center insulator cracks circumferential inside the plug, this allows the insulator to slide down and contain the gap so no spark. the trap is when you pull the plug and turn it up to check, the insulator slides back where it belongs. so you clean the plug reset the gap check the lead and refit still no ignition . pain in the proverbial if you shake the plug though you can here it sliding
Nicely done Stu. I don't know about boat engines but some car engines have different plugs specified for different cylinders. Mitsubishi Magnas with V6 engines had the rear cylinders specified as iridium plugs, and the front cylinders as normal plugs. That was because you have to undo engine mounts and rock the motor forward to change the rear plugs -with iridium plugs it meant they are a 'change at 100K Km ' job. the front plugs were 40K Km change out. Smart people used iridium in the front cylinders as well - the net cost was the same in the end.
Hey Ron, it does sound like a makes a lot more sense to just change them all to iridium. I can't imagine keeping track of two different replacement intervals! By the way, I still can't find that procedure for making the sync tool in that manual. I really must get those vids on your motor done soon...
I know it is in there as none of the generic manuals have it in them. Basically 2 instrument alligator clips with 50mm of solid core wire soldered to them .. You put one clip on each butterfly shaft and adjust the linkage so that both shafts start moving at exactly the same time . The wire 'pointers' make it easier to see when the shafts start to move. If you make them and try it out you will see what I mean.
Ah, that's very interesting to hear and makes a lot of sense. A while ago I had a small problem with my Alfa where the gear knob would rotate past straight and I thought I would do the same - shim it so it was tight just at the point where it was straight. Before I did that though it went to the factory for some warranty work and they must have noticed that problem too. When it came back they had glued it on with so much glue that it has run down into the lever you need to lift to go into reverse. Geniuses!
Damn Stu you went to town on spark plugs. I've been waiting for this video to come out and you did better than I thought was possible! I've never heard of or seen that spark plug you showed with out the electrode. That is a crazy looking plug! GREAT JOB
I found a Mark Lipski in Texas. (TCB-Traction Controlled Braking) made a extended banjo bolt that turns motorcycle brakes to act like ABS. But, he also invented a car head gasket with controlled computer spark (4 sparks on head gasket-rather than just one spark in spark plug, making spark plugs obsolete. He just puts a bolt in existing spark plug holes, runs better too)
Wow Stu, When I first pulled this up this morning my first thought how much can there be to talk about a spark plug? My wrong on that thought. Very interesting video. My chainsaw/weedeater video I edit cut it over and over and it's still over 20 minutes long. There is allot going on with these than I thought. I'm still not there yet too. I guess I'll have to split it up into several videos not to put folks to sleep. Haha
Thanks Tim, splitting big subjects up is a good way to go. It also helps people who are searching for a specific part of the problem they need to solve.
good video stu . i even learned something. good to note those crush washers should be replaced if you are going to reuse the plug. years ago any parts store had them now its a special order item. just buy a new plug. also not only do resistor plugs cut rfi but also using a non-resistor in a resistor designed system reduces component life due to higher current flow. learned that the hard way.
I agree that ideally a crush washer should be replaced, but I've certainly seen hundred of plugs go back in with the original washers without problem. Resistive plugs definitely reduce the current flow, that's for sure.
Mate. the amount of videos you've uploaded is getting huge? i've been watching your channel now for a while. getting movie star status? lol Happy days. we still need to have a beer ? next time you're in Melbourne.. Cheers.
Stu; I read other comments because I thought I was alone about plugs. Does this index method refer to Gasoline Vehicles cars and trucks too. And you didn't cut a Plug open length wise so we could see, LOL. Well thank you for my new Plug confusion. I appreciate the knowledge you bestowed upon me Mate !! Keep up the good work. If you get the time let me know the answer to my question. Thank you.... Angelo
I've only seen it done on E-TEC outboards, but John below mentioned they used to do it on their race cars to so I imagine it can help with any direct injection motor. I love cutting things in half, I can't believe I didn't! ;)
Indexing plugs on most engines will not gain anything, except a few more expletives floating on the wind! It is an absolute pain to do for no gain. Most of the common engines that need the plugs indexed run lean burn for economy or emissions reasons- so in cars you are talking about Hondas, Valiants (the ELB badged ones) and almost all the Orbital Engines based motors ( which are really two strokes running very lean oil mix and air injected fuel mix) . The fuel air mix is normally too lean to ignite except in a specific area, which as Stu mentioned is typically within close proximity to the fuel injection point or in the Hondas, a small firing chamber that held a richer mixture that set off the main cylinder mix.On a top fuel engine we indexed the plugs so we had two flame fronts propagating away from each other as much as possible. We melted pistons or stripped blower belts if we got that wrong !
By the way I had a friend drop by today who has worked on the type of gear shifter I've been having trouble getting to go into throttle only position it's a mercury Quick Silver and he took it completely apart and discovered that I had made a small mistake when I put the ball bearing in the lower hole instead of the upper hole in the throttle only shaft, now it works like a charm, just wanted to let you know that good news : )
Thanks for the update on the plug facing the injectors on an Outboard Motor. Marine Mechanics would Know important factors by the Knowledge & Training. Keep the Information going for the DIYers.
Comparing same spark plug brand model and heat range, if you don't run electronics onboard will a non resistor type plug fire a much better amount of electricity, healthier gap jump, stay much cleaner whatever compared to a resitor type plug ?
I have a Suzuki Df90a, it calls for a NGK DCPR6E, can I use the Iridium spark plug DCPR6EIX? It’s the same plug just in Iridium plug. It’s the up grade plug!
I waited all day for this upload mate.Great stuff as usual.If only I can sort why my Yamaha 30cv keeps fouling plugs I'd be a happy camper.I tried installing NGK Br7hs10 plugs for the same result.The bloody thing has done it since new.Must be a 2cyl Yamaha thing.Other than the fouling it's been a great little motor.
Do you do much idling / trolling while fishing? Somebody asked me once about video on setting an outboard up for low speed running. It's a tough thing to do though as you may also need to run at speed to get back to the boat ramp, but less oil and a hotter plug may help.
Dangar Marine that was me with the 15 hp 1978 Johnson. A tad bit less oil as you suggested and she's been running beautiful at WOT and trolling. Engine temp is also perfect. I can't divide my engine performance between trolling and high-speed because I do an equal amount of both. It's a bit of both all day long. Running a tad bit less oil has also cut way down on the wet exhaust dribble out of the lower exhaust port hole. I would run two engines if I could but I have a 14 foot tinny and I'm a pretty big guy. If I twist the tiller pretty hard everything from the bow of boat winds up in my lap including my dog.... lmao. I have an electric trolling motor but it's not variable speed and I get sick and tired of dealing with a battery. The fish in the reservoirs I fish do not get spooked by the gas motor very easily. They are heavily used recreational Reservoirs :-) .. Thanks again Stu
Dangar Marine,I never troll or idle for prolonged periods.Im always running fresh unleaded fuel using yamalube mixed at 100:1.Gave tried 70:1 and 50:1 for the same result (I thought it would get worse)When driving through Wash zones, 4knot zones and then i come out of them and accelerate it hesitates and carries on a bit until it clears up and smooths out which usually lasts a minute or so.You only have to be at those slower speeds for a few minutes for it to happen.As you know br8hs-10 is the recommended plug and have run br7hs-10 for pretty much the same result.What are your experiences with the Yamaha cv's you've worked on/driven? Do they foul plugs? And do you know what the coldest plug I could safely go without pre-ignition? Any help is much appreciated mate or anyone else reading that may be of help. Cheers.
Fabian, I have no experience with Yamahahaha s , but being a carb'd engine there are some things to check before playing with the plug range. 1: if you are not running at sea level your main jets may need changing to a smaller size, especially if your run on lakes more than 1000ft above sea level. If you don't change the jets for the higher altitude you will always be rich on the mix.2: Check , or have checked, the fuel bowl levels. Stu covers this in one of his videos. It is not common but it does happen that the assembly people get the carbs set wrong. Maybe just put some carb kits through the motor so you know they are right internally New needles and seats, floats etc.3: you may need to sync the carbs- it doesn't take much of difference in the butter flys opening to make what sounds and feels like misfire to occur.
Hi Dangar Marine. This is another great video I'm learning a ton from your content. I have a 1999 Nissan 25hp two stroke outboard on my boat and I'm going through spark plugs after only about 5 hours of run time. I tend to idle and run at lower RPMs often where I fish. After a while my motor doesn't want to stay running and will quit at idle and i notice my plugs are brown and maybe just a bit oily, once I put the new plugs in it runs great for about another 5ish hours of start and stop fishing. Would you recommend I try a bit hotter plug and maybe lean out my fuel oil mix a bit? Thanks in advance!
You could try both really. It's a tough call with reducing the oil as although you do a lot of idling, I presume you run at full speed there and back so you will need the correct oil mixture just for that part of the trip. You might find a cheap electric trolling motor is the best solution to your problem.
Thanks for all the great videos, they (and you) have certainly helped me diagnose and fix lots of issues with my motors. I do have a question which I hope you could advise me on. I have a couple of 1983 Mariner 60HP two stroke, two cylinder motors (apparently they were build by Yamaha). I have seen many similar motors here on RUclips that have stickers indicating the fuel/oil ratio as 100 : 1. Unfortunately my motors don't have this sticker. Most two stroke outboard owners say that the correct ratio is 50 : 1. I've been using 50 : 1 for as long as I've had these motors (less than two years) and it seems as if it fouls the plugs. The plugs are always very oily and on one occasion a plug just died while on the water. A mechanic did tell me once that there's too much oil in the fuel. What's your opinion on this, or do you know what the correct fuel/oil ratio should be? Unfortunately I don't have a service manual for these motors.
Gday Stu , great informative vid as usual mate , very interesting section on the indexing of plugs this i absorbed and today will check the indexing on my wifes 280 zx nissan . one question though , they suggest not trying to gap the newer iridium plugs why is this the rule on those , cheers m8 thx
I've only ever seen indexing required on E-TECs, but I presume it could make a difference on any engine with side injection. Makes sense about iridium plugs as they have a very fine centre electrode which could be very easily damaged during gapping.
recently ac delco discontinued the $9 single coating platinum plug for my car because it was'nt lasting the 40k-80k miles as advertised. it's a .050 gap and only lasts at best 10k miles because the electrode would be totally worn down the porcelain. so now they recommend their double coated platinum one for $10. from what i understand the electrode has gotten smaller to reduce em pollution like you said and burn hotter for less chance of misfire in fuel injected engines.
Howzit Stu. That's a great video, as usual. At 8:35 in the vid, you speak about going one or two hotter. I have been thinking about that because I have and older Mariner/Yammie 40 (6E9) and I do a lot of slow puttering around. I have the problem that I need to clean (or replace) my plugs everytime I go out. The plugs seem to get quite oiled up. I have also tried decreasing the oil content to 100:1, yet the problem still exists. How do you feel about going 2 hotter (from a 8 to a 6), or should I try just 1 hotter and see what happens first?
So yesterday I spent a regular day fishing in the bay. A little bit of high speed, but mostly a lot of slow coming and going. Upon checking the plugs, they were still rather oily so I cleaned them with a spray of "carb cleaner", which works well. Could I do any damage if I went 1 hotter again? I just tried a BP7ES and really would like to try a"6". What do you think/suggest ?
It is really only the plugs that will get hot not the engine itself but if the plug gets too hot it can cause pre-ignition so if you do go to 6's make sure you keep and ear out for any knocking.
Hi Mate , talking plugs , I had a massive lose of power thismorning behing lion Island, limped back to brissy waters , to find cylinder plug No 2 on my 40 yammy , the electrodes on the plug were touching???? Can you shed some light on this please..????
Thanks for the response Stu. On a Tohatsu Tldi is it normal for a fuel pressure test gauge(non fluid filled) to jump around quite a lot whilst the engine is running?
Thanks Stu :) - a lot of your content can be transposed to motorcycles and even cars. I'm afraid I have petrol in my head and diesel in my veins (these days I drive double deck London buses at the weekends for fun!), so anything oily has a space in my heart. You are doing good stuff mate, please keep them coming!
Hi Danger Marine, I bought a Tohatsu 50hp 2022 model on may 15th 2022. It was installed by the dealer and delivered it to me. It has hardly ran better since. Twice dealer try to fix it as he says but he does not want to know anymore. Its like it working on 2 cylinders only. Hardly goes to 300rpm. I put antifreeze in it thinking there could be water in fuel tank, but it did not help.I checked the spark and its very weak spark and light orange colour. Can you help please as to what could be the problem and how to fix it. Thank you
Im using B8HS 10 SPARK PLUGS PLUGS which .040" gap in old evinrude 40 hp 1975 And the manual say evinrude 1975 using .030 gap and ive rough idle and rough at low speed in motor do u thing the gap makes different?
My question, based on Stuart's explanation of it, would be... Would it make sense to periodically pull the 2 plugs and swap positions between plug holes?
Mostly I see it on small two cylinder motors where they are trying to keep the cost down. Having a single coil like that is cheaper than two individual ones. Good point Stan, swapping the plugs across cylinders does make sense to help them wear evenly.
A GM Holden engine here in Australia uses the double ended coil system on a lot of the V6 engines. It is done both as a cost cutting measure and also as a space saving measure. The cost cutting is more than the extra 3 coils + wiring though. The ECU only needs 3 FETs to be installed, the ECU CPU needs less outputs, less solder joints etc. It is not always done for cost reasons, the lower parts count adds to the reliability - there is less to go wrong. The coils fire the plugs at around 50Kv , and as STu stated - plugs need about 15-25Kv to fire- so the one being fired 'wrong way' is no issue. The issue you have is if one plug fails open circuit you lose 2 cylinders.But 'wasted spark' has been used from the early days of Kettering ignition as well- one BSA 250 twin had the points cam on the crank shaft rather than the cam shaft. Those points earthed both coils at the same time, so both plugs fired every rotation. No real problem as one cylinder was always on the exhaust stroke. But if either coil broke down- and they did -often- it was hell to diagnose.
Australian built EF (1994-1996) and AU (1998-2002) ford falcons also use a waste spark ignition system. Coincidently the mighty AU falcon is arguably the greatest car in existence. Ugly as dog shit but nigh on indestructible.
Hi Stu, would you risk installing iridium spark plugs? Advantages? Disadvantages? I'm worried about melting a piston top on a 2 stroke Force 120. Thanks.
What about trolling in cold water? In my case hours of idle speed in ~5°C water temp. Doesn't take too long until my 30yr old 2-stroke starts to smoke and idle gets rough due to cold engine temp and unburned oil. Can not install much hotter plugs because driving full throttle to the fishing spot takes a while. Any tricks to make the old 2-stroke run hotter while idling?
Danger.....I wished you touched upon whether you can use any kind of plug ie Automotive v Marine in an Outboard engine Also you mentioned indexing on FI but didn't say anything about Carburetored outboard
Fantastic upload Stu. Have you had a chance to test a hydrofoil yet, i"m eager to hear an honest opinion on them? Have you had much experience with gear driven oil injection pumps over oiling or leaking from the oil seal?
Thanks mate. No, haven't done the hydrofoil yet but it is sitting in the workshop ready to go so it won't be long. I haven't seen an oil pump leaking, it is very possible, all seals fail eventually. Some are adjustable by a threaded linkage so if it is adding too much oil they can often be "turned down"
Hi Stu, how do you check spark on a face gap spark plug? In another video you had the normal spark plug connected to the cable and grounded on the outboard and as you cranked the engine we can see the spark jump from the electrode to the ground. But with a face gap version, there is no ground plate. So can we still do this simple test and would there be a spark from the electrode to the housing/thread section instead? Thanks.
So basically I have a 25 HP 2 stroke Mercury that came with a used boat I bought. Electric starter motor works but the engine doesn't run. Checked fuel lines, all good. Did the spark test and no spark on either of the spark plugs. Previous owner reckons it is the powerpack. Will do some more troubleshooting before I replace the powerpack.
Oh I do have a question on spark plugs. Mercury Marine service manual shows a view on spark plug conditions with my two stoke. With wet plugs after it run shows a rich burn. I know it's better to be a little rich rather than lean and running at a idle with muffs could be why? Just need you're thoughts on this. Thanks
The carb will vary its air fuel mixture through its rev range. You might be able to just lean out the idle mixture screw if it is too rich, this won't greatly affect the full throttle mixture.
Yeah man whenever I pulled my plugs while running on muffs they are always drenched in oil. I think Stu mentioned in vid to run at average speed for a while then pull n check plugs for a true result
As a two stoke gets older would you tend to a colder or hotter spark plug? Which is best for cold starting a cranky Johnson 85 circa 78 that runs sweet once warmed up?
I would stick with the factory recommendation. A hot plug doesn't have a hotter spark, it just gets hotter after a while of running so it won't affect your hard starting. Hard starting generally comes down to poor compression, bad reed valves, dirty carburettor or a faulty choke mechanism.
You honestly have the most through marine repair videos on RUclips. Made your DVA adapter and used it a lot this summer to replace CDI units. Keep up the good work, always intrigued.
Glad I could help!
WOW!! And here I thought all the spark plug did was deliver the spark, so much here that I did not know and very important stuff, your second career could very well be that of a teacher, I've always said that there are many experts in life but very few who can explain a subject in such a way that it sticks to you like glue, your one of these people, thank you
Thanks Adrien. My second career *is* that of a teacher! RUclips lets you reach many more students than the classroom does. :)
God, never knew this information was available thru the part number alone. Thanks for breaking everything down for us. 10/10 mate
Glad you liked it!
@@DangarMarine absolutely! Curious if you could take a peek at the last video I uploaded, just to see if that’s how my carb should be functioning. Sorry to bother you!
-Gray
One of the best videos I have ever seen. Fantastic information in a concise manner. Thank you!
Dude can I get college credits! Wow blown away how informative and simple you break it down. You should make a multiple choice quiz after each video ✌️
Great tutorial on spark plugs Stu. Especially the part about running the motor at speed and then pulling the plug right away to examine it. Very good information!
Thanks Jack, glad you enjoyed it. :)
And to think I've just been twisting them in until they feel "about right" my whole life... Thanks Stu!
You wouldn't be alone in that! :)
@@DangarMarine p
Great presentation man! You’re too humble in saying you don’t know that much about the subject.Your knowledge is impressive!
Fame at last! Thanks for the shout out Stu.
Great vid - learnt loads as always!
Welcome Paul, glad you enjoyed the vid. :)
I'll just say I've been watching your videos for a long time and have fixed many outboards because of you saving me $1000s in mechanic fees. Thank you for that. I would like to through a suggestion for a video dealing with adjustment of loose steering on cables. Some time would be nice again thanks for your sharing of knowledge!
Hi mate, if the steering is very loose, it can only really be tightened at the outboard itself, I'll do a vid one day.
I watch all your videos and you have helped me so much. Thank you for your service and time to help so many people.
You're welcome Joseph. :)
Dangar Marine I have a 120 Mercury force on my Bayliner and you have inspired me to find a bigger motor and rebuild it
your videos have help me so much in understanding different systems, thank you ( United States, Indiana )
You're welcome Brent. :)
This was an awesome breakdown of the Sparkplug. I have not given them much thought other than replacing them in timed intervals.
Thanks Zach, there certainly is more to them than meets the eye.
Wow..had no idea it mattered where the tip of the spark plug was facing inside the head!!
Man you have made my day..you have taught me more in your videos than i have ever heard about before..
Pls..write some books for people who want to do things correctly..
Thanks again ..
Another winner, Stu. Thanks very much. Always thought those gapless plugs made a lot of sense. Several Mercury 2 strokes we had in the Eighties specced them.
Thanks mate, those plugs do seem pretty reliable.
Have a look in the Johnson 50 - they are gapless as spec'd. Also aircraft engines typically use gapless or face firing plugs - sometimes for piston clearance reasons, usually for the reliability factor. Its a bit hard to stop and check whats wrong at 10,000ft!
just caught up with this video Stu very informative as usual 1 uncommon failure I want to share is when the center insulator cracks circumferential inside the plug, this allows the insulator to slide down and contain the gap so no spark. the trap is when you pull the plug and turn it up to check, the insulator slides back where it belongs. so you clean the plug reset the gap check the lead and refit still no ignition . pain in the proverbial if you shake the plug though you can here it sliding
Nicely done Stu. I don't know about boat engines but some car engines have different plugs specified for different cylinders. Mitsubishi Magnas with V6 engines had the rear cylinders specified as iridium plugs, and the front cylinders as normal plugs. That was because you have to undo engine mounts and rock the motor forward to change the rear plugs -with iridium plugs it meant they are a 'change at 100K Km ' job. the front plugs were 40K Km change out. Smart people used iridium in the front cylinders as well - the net cost was the same in the end.
Hey Ron, it does sound like a makes a lot more sense to just change them all to iridium. I can't imagine keeping track of two different replacement intervals! By the way, I still can't find that procedure for making the sync tool in that manual. I really must get those vids on your motor done soon...
I know it is in there as none of the generic manuals have it in them. Basically 2 instrument alligator clips with 50mm of solid core wire soldered to them .. You put one clip on each butterfly shaft and adjust the linkage so that both shafts start moving at exactly the same time . The wire 'pointers' make it easier to see when the shafts start to move. If you make them and try it out you will see what I mean.
The idea makes sense, I just can't find it in the manual. I'll have another look through and get it finished up for you!
no doubt knocked that one out of the park. thank you for such infomative videos
wow it so good looking back on the videos but loved the info well done stu
Glad you enjoyed it
Such good content Stu. Damn near an expert in that you are well informed and resourceful.
Thanks mate, glad you like it. :)
Great video Stu. We used to use shims to index plugs on our race cars and I've been doing on all casket-ed plugs. Thanks!
Ah, that's very interesting to hear and makes a lot of sense. A while ago I had a small problem with my Alfa where the gear knob would rotate past straight and I thought I would do the same - shim it so it was tight just at the point where it was straight. Before I did that though it went to the factory for some warranty work and they must have noticed that problem too. When it came back they had glued it on with so much glue that it has run down into the lever you need to lift to go into reverse. Geniuses!
Holy crap, Stu! I knew I didn't know a lot about spark plugs, but know I know how much I didn't know! Love all the videos!
"My crappy diagram," says Stu. Then a wonderful illustration comes in to the shot. Brilliant.
Thanks Brian. :)
Your videos are so bloody good. Thank you so much Stu!
Awsome that you mentioned indexing. Great video.
Thanks Andy. :)
Awesome video Stu, learnt quite a bit, cheers
Thanks Cliff.
Are u a aussie
That was a quick 20 minutes, surprised me.thanks stu
Glad it didn't drag on! ;)
Great Video STU!! Had no idea that much went into plugs and all the numbers and letters keep it up!! Cheers!
Thanks Scotty, there sure is more to them than meets the eye!
Great video, noticed the beer move and even disappeared.. cheers!
Thanks mate. That beer didn't disappear, I know exactly where it went. ;)
Damn Stu you went to town on spark plugs. I've been waiting for this video to come out and you did better than I thought was possible! I've never heard of or seen that spark plug you showed with out the electrode. That is a crazy looking plug! GREAT JOB
Thanks Jim, I must admit, those plugs took me by surprise when I first saw them too.
Resistive spark plugs are a life saver when your boat radio is running off the same battery used to start the outboard. Solved a huge headache for me.
Thank you for such a great video. I have learned more about sparkplugs
Glad it was helpful!
Thanks Stu I learned a lot from this vid, thanks from Canada
You're welcome Kim, glad you enjoyed. :)
thanks this video was a great help love your channel keep it up love to see new content
Glad it helped. :)
I found a Mark Lipski in Texas. (TCB-Traction Controlled Braking) made a extended banjo bolt that turns motorcycle brakes to act like ABS. But, he also invented a car head gasket with controlled computer spark (4 sparks on head gasket-rather than just one spark in spark plug, making spark plugs obsolete. He just puts a bolt in existing spark plug holes, runs better too)
Fantastic video, you really educated me on spark plugs. THANKS FREIND.
You're welcome Ronald. :)
Wow Stu, When I first pulled this up this morning my first thought how much can there be to talk about a spark plug? My wrong on that thought. Very interesting video. My chainsaw/weedeater video I edit cut it over and over and it's still over 20 minutes long. There is allot going on with these than I thought. I'm still not there yet too. I guess I'll have to split it up into several videos not to put folks to sleep. Haha
Thanks Tim, splitting big subjects up is a good way to go. It also helps people who are searching for a specific part of the problem they need to solve.
Tim's Workshop
I have an EFI motor on order. Interesting about the open gap of the plug facing the injector. Thanks for sharing.
NGK plugs are the way to go the best.
good video stu . i even learned something. good to note those crush washers should be replaced if you are going to reuse the plug. years ago any parts store had them now its a special order item. just buy a new plug. also not only do resistor plugs cut rfi but also using a non-resistor in a resistor designed system reduces component life due to higher current flow. learned that the hard way.
I agree that ideally a crush washer should be replaced, but I've certainly seen hundred of plugs go back in with the original washers without problem. Resistive plugs definitely reduce the current flow, that's for sure.
Mate. the amount of videos you've uploaded is getting huge? i've been watching your channel now for a while. getting movie star status? lol
Happy days. we still need to have a beer ? next time you're in Melbourne..
Cheers.
Thanks Danny, a beer some time sounds awesome. :)
Concise, precise, pragmatic. Thank you.
Stu; I read other comments because I thought I was alone about plugs. Does this index method refer to Gasoline Vehicles cars and trucks too. And you didn't cut a Plug open length wise so we could see, LOL. Well thank you for my new Plug confusion. I appreciate the knowledge you bestowed upon me Mate !! Keep up the good work. If you get the time let me know the answer to my question. Thank you.... Angelo
I've only seen it done on E-TEC outboards, but John below mentioned they used to do it on their race cars to so I imagine it can help with any direct injection motor. I love cutting things in half, I can't believe I didn't! ;)
Thank-u for the reply to my questions. If it doesn't turn into to much trouble I'll index the plugs on my Ford Bronco !!.
Indexing plugs on most engines will not gain anything, except a few more expletives floating on the wind! It is an absolute pain to do for no gain. Most of the common engines that need the plugs indexed run lean burn for economy or emissions reasons- so in cars you are talking about Hondas, Valiants (the ELB badged ones) and almost all the Orbital Engines based motors ( which are really two strokes running very lean oil mix and air injected fuel mix) . The fuel air mix is normally too lean to ignite except in a specific area, which as Stu mentioned is typically within close proximity to the fuel injection point or in the Hondas, a small firing chamber that held a richer mixture that set off the main cylinder mix.On a top fuel engine we indexed the plugs so we had two flame fronts propagating away from each other as much as possible. We melted pistons or stripped blower belts if we got that wrong !
By the way I had a friend drop by today who has worked on the type of gear shifter I've been having trouble getting to go into throttle only position it's a mercury Quick Silver and he took it completely apart and discovered that I had made a small mistake when I put the ball bearing in the lower hole instead of the upper hole in the throttle only shaft, now it works like a charm, just wanted to let you know that good news : )
Once one Adrien! It is very easy to make that kind of mistake with these fiddly components.
All thanx our marvelous teacher
Thanks for the update on the plug facing the injectors on an Outboard Motor.
Marine Mechanics would Know important factors by the Knowledge & Training.
Keep the Information going for the DIYers.
Comparing same spark plug brand model and heat range, if you don't run electronics onboard will a non resistor type plug fire a much better amount of electricity, healthier gap jump, stay much cleaner whatever compared to a resitor type plug ?
I have a Suzuki Df90a, it calls for a NGK DCPR6E, can I use the Iridium spark plug DCPR6EIX? It’s the same plug just in Iridium plug. It’s the up grade plug!
Another great video. Thanks Stu.
Thanks Greg!
I waited all day for this upload mate.Great stuff as usual.If only I can sort why my Yamaha 30cv keeps fouling plugs I'd be a happy camper.I tried installing NGK Br7hs10 plugs for the same result.The bloody thing has done it since new.Must be a 2cyl Yamaha thing.Other than the fouling it's been a great little motor.
Do you do much idling / trolling while fishing? Somebody asked me once about video on setting an outboard up for low speed running. It's a tough thing to do though as you may also need to run at speed to get back to the boat ramp, but less oil and a hotter plug may help.
Dangar Marine that was me with the 15 hp 1978 Johnson. A tad bit less oil as you suggested and she's been running beautiful at WOT and trolling. Engine temp is also perfect.
I can't divide my engine performance between trolling and high-speed because I do an equal amount of both. It's a bit of both all day long. Running a tad bit less oil has also cut way down on the wet exhaust dribble out of the lower exhaust port hole.
I would run two engines if I could but I have a 14 foot tinny and I'm a pretty big guy. If I twist the tiller pretty hard everything from the bow of boat winds up in my lap including my dog.... lmao.
I have an electric trolling motor but it's not variable speed and I get sick and tired of dealing with a battery. The fish in the reservoirs I fish do not get spooked by the gas motor very easily. They are heavily used recreational Reservoirs :-) .. Thanks again Stu
Dangar Marine,I never troll or idle for prolonged periods.Im always running fresh unleaded fuel using yamalube mixed at 100:1.Gave tried 70:1 and 50:1 for the same result (I thought it would get worse)When driving through Wash zones, 4knot zones and then i come out of them and accelerate it hesitates and carries on a bit until it clears up and smooths out which usually lasts a minute or so.You only have to be at those slower speeds for a few minutes for it to happen.As you know br8hs-10 is the recommended plug and have run br7hs-10 for pretty much the same result.What are your experiences with the Yamaha cv's you've worked on/driven?
Do they foul plugs? And do you know what the coldest plug I could safely go without pre-ignition?
Any help is much appreciated mate or anyone else reading that may be of help.
Cheers.
Fabian, I have no experience with Yamahahaha s , but being a carb'd engine there are some things to check before playing with the plug range. 1: if you are not running at sea level your main jets may need changing to a smaller size, especially if your run on lakes more than 1000ft above sea level. If you don't change the jets for the higher altitude you will always be rich on the mix.2: Check , or have checked, the fuel bowl levels. Stu covers this in one of his videos. It is not common but it does happen that the assembly people get the carbs set wrong. Maybe just put some carb kits through the motor so you know they are right internally New needles and seats, floats etc.3: you may need to sync the carbs- it doesn't take much of difference in the butter flys opening to make what sounds and feels like misfire to occur.
Is it worth putting in iridium/platinum/unobtanium spark plugs for an outboard?
Thanks stu another awesome vid good informative advice
that was very informative, wish i would of seen it before i took them out .thank you Dan your the greatest,
Hi Dangar Marine. This is another great video I'm learning a ton from your content. I have a 1999 Nissan 25hp two stroke outboard on my boat and I'm going through spark plugs after only about 5 hours of run time. I tend to idle and run at lower RPMs often where I fish. After a while my motor doesn't want to stay running and will quit at idle and i notice my plugs are brown and maybe just a bit oily, once I put the new plugs in it runs great for about another 5ish hours of start and stop fishing. Would you recommend I try a bit hotter plug and maybe lean out my fuel oil mix a bit? Thanks in advance!
You could try both really. It's a tough call with reducing the oil as although you do a lot of idling, I presume you run at full speed there and back so you will need the correct oil mixture just for that part of the trip. You might find a cheap electric trolling motor is the best solution to your problem.
What about Resistor In a spark plug?
Is that good for carburetor
Yes, fine for carburettor.
You are very thorough. You would be a great teacher!
Does the cone depth have anything to do with heat range? Thanks
hey stu. my 1990 merc 70hp uses flat top plugs. do u know the benifits or cons regarding these types of plugs?
They don't wear as much which is good. They don't have a great spark at idle, but they work well at high speed.
Can you interchange regular spark plugs with the open face plugs, and vice versa?
Who in the world will actually dislike this video? Good job man!
good to watch, usual high standard :)
Thanks Jamie!
Thanks for all the great videos, they (and you) have certainly helped me diagnose and fix lots of issues with my motors. I do have a question which I hope you could advise me on. I have a couple of 1983 Mariner 60HP two stroke, two cylinder motors (apparently they were build by Yamaha). I have seen many similar motors here on RUclips that have stickers indicating the fuel/oil ratio as 100 : 1. Unfortunately my motors don't have this sticker. Most two stroke outboard owners say that the correct ratio is 50 : 1. I've been using 50 : 1 for as long as I've had these motors (less than two years) and it seems as if it fouls the plugs. The plugs are always very oily and on one occasion a plug just died while on the water. A mechanic did tell me once that there's too much oil in the fuel. What's your opinion on this, or do you know what the correct fuel/oil ratio should be? Unfortunately I don't have a service manual for these motors.
Gday Stu , great informative vid as usual mate , very interesting section on the indexing of plugs this i absorbed and today will check the indexing on my wifes 280 zx nissan . one question though , they suggest not trying to gap the newer iridium plugs why is this the rule on those , cheers m8 thx
I've only ever seen indexing required on E-TECs, but I presume it could make a difference on any engine with side injection. Makes sense about iridium plugs as they have a very fine centre electrode which could be very easily damaged during gapping.
I learn something every time! Thank you! I'll never look at them the same way again.
There certainly is more to them than meets the eye!
This was an outstanding video
Thanks John, glad you liked it. :)
recently ac delco discontinued the $9 single coating platinum plug for my car because it was'nt lasting the 40k-80k miles as advertised. it's a .050 gap and only lasts at best 10k miles because the electrode would be totally worn down the porcelain. so now they recommend their double coated platinum one for $10. from what i understand the electrode has gotten smaller to reduce em pollution like you said and burn hotter for less chance of misfire in fuel injected engines.
Interesting that they weren't lasting, good that they came out with a new plug that isn't much more expensive though.
Howzit Stu. That's a great video, as usual. At 8:35 in the vid, you speak about going one or two hotter. I have been thinking about that because I have and older Mariner/Yammie 40 (6E9) and I do a lot of slow puttering around. I have the problem that I need to clean (or replace) my plugs everytime I go out. The plugs seem to get quite oiled up. I have also tried decreasing the oil content to 100:1, yet the problem still exists. How do you feel about going 2 hotter (from a 8 to a 6), or should I try just 1 hotter and see what happens first?
I would certainly start by trying one hotter and see how that goes, particularly if you do some high speed running on the way out and back.
So yesterday I spent a regular day fishing in the bay. A little bit of high speed, but mostly a lot of slow coming and going. Upon checking the plugs, they were still rather oily so I cleaned them with a spray of "carb cleaner", which works well.
Could I do any damage if I went 1 hotter again? I just tried a BP7ES and really would like to try a"6". What do you think/suggest ?
It is really only the plugs that will get hot not the engine itself but if the plug gets too hot it can cause pre-ignition so if you do go to 6's make sure you keep and ear out for any knocking.
Thanks mate. I understand perfectly. :)
Hi Mate , talking plugs , I had a massive lose of power thismorning behing lion Island, limped back to brissy waters , to find cylinder plug No 2 on my 40 yammy , the electrodes on the plug were touching???? Can you shed some light on this please..????
What should I gap QL78YC plugs to my 1998 Johnson 70hp same plugs it recommends on OMC sticker
Thanks for the response Stu. On a Tohatsu Tldi is it normal for a fuel pressure test gauge(non fluid filled) to jump around quite a lot whilst the engine is running?
Yes, for carburetted outboards with a mechanical pump the pressure isn't stable. For EFI outboards it should be steady at around 40 PSI.
Thanks Stu, mine is direct injected so i'm guessing the fuel pump is playing up.
Cool show, cool music. Thanks.
Ten outta ten again. Thanks.
Very nice and instructional vid, a bit hard to follow your "speedy talking" for a dutchman, but get used to it near the end.
Thanks Willem, yes, ways of speaking can take a while to get used to.
keep going brother .. wacthing from kuwait 😎
I don't have a boat, I will never have a boat, yet I love Stu's videos - watching from the UK.
fulwell1 buy one 😉
Thanks guys, glad you are enjoying the vids (boat or not!) :)
Not much need for one where I am in London - - - when I win the lottery and move to Australia, than I will.
Thanks Stu :) - a lot of your content can be transposed to motorcycles and even cars. I'm afraid I have petrol in my head and diesel in my veins (these days I drive double deck London buses at the weekends for fun!), so anything oily has a space in my heart. You are doing good stuff mate, please keep them coming!
Hi Danger Marine,
I bought a Tohatsu 50hp 2022 model on may 15th 2022. It was installed by the dealer and delivered it to me. It has hardly ran better since. Twice dealer try to fix it as he says but he does not want to know anymore. Its like it working on 2 cylinders only. Hardly goes to 300rpm. I put antifreeze in it thinking there could be water in fuel tank, but it did not help.I checked the spark and its very weak spark and light orange colour. Can you help please as to what could be the problem and how to fix it.
Thank you
Im using B8HS 10 SPARK PLUGS PLUGS which .040" gap in old evinrude 40 hp 1975
And the manual say evinrude 1975 using .030 gap and ive rough idle and rough at low speed in motor do u thing the gap makes different?
Great video!
What kind of engine(s) would use the wasted spark setup?
RichE
My question, based on Stuart's explanation of it, would be... Would it make sense to periodically pull the 2 plugs and swap positions between plug holes?
Mostly I see it on small two cylinder motors where they are trying to keep the cost down. Having a single coil like that is cheaper than two individual ones. Good point Stan, swapping the plugs across cylinders does make sense to help them wear evenly.
In automotive the applications they were used in the mid 90s through mid 2000s on economy minded engines. The GM 4 cylinders used them extensively.
A GM Holden engine here in Australia uses the double ended coil system on a lot of the V6 engines. It is done both as a cost cutting measure and also as a space saving measure. The cost cutting is more than the extra 3 coils + wiring though. The ECU only needs 3 FETs to be installed, the ECU CPU needs less outputs, less solder joints etc. It is not always done for cost reasons, the lower parts count adds to the reliability - there is less to go wrong. The coils fire the plugs at around 50Kv , and as STu stated - plugs need about 15-25Kv to fire- so the one being fired 'wrong way' is no issue. The issue you have is if one plug fails open circuit you lose 2 cylinders.But 'wasted spark' has been used from the early days of Kettering ignition as well- one BSA 250 twin had the points cam on the crank shaft rather than the cam shaft. Those points earthed both coils at the same time, so both plugs fired every rotation. No real problem as one cylinder was always on the exhaust stroke. But if either coil broke down- and they did -often- it was hell to diagnose.
Australian built EF (1994-1996) and AU (1998-2002) ford falcons also use a waste spark ignition system. Coincidently the mighty AU falcon is arguably the greatest car in existence. Ugly as dog shit but nigh on indestructible.
Another good video mate
Thanks for sharing 🇧🇧 👉🏾 🇨🇦 👍🏽
Wow 😲 😳 I had no idea plugs were so interesting 👊. Thank you
What is the gap supposed to be on a spark plug for 150 Yamaha out two stroke
The last two digits of the NGK spark plug number are generally the gap. 10 is common being 1 millimetre.
I have a mercury blue band 50 horsepower 4 cylinder on my speedboat what would be the best plug
Hi Stu, would you risk installing iridium spark plugs? Advantages? Disadvantages? I'm worried about melting a piston top on a 2 stroke Force 120. Thanks.
Comprehensive my new go to vid 👍thanks mr danger 💥💥💥
What about trolling in cold water? In my case hours of idle speed in ~5°C water temp. Doesn't take too long until my 30yr old 2-stroke starts to smoke and idle gets rough due to cold engine temp and unburned oil.
Can not install much hotter plugs because driving full throttle to the fishing spot takes a while. Any tricks to make the old 2-stroke run hotter while idling?
Brilliant.
Thanks mate.
Danger.....I wished you touched upon whether you can use any kind of plug ie Automotive v Marine in an Outboard engine
Also you mentioned indexing on FI but didn't say anything about Carburetored outboard
I've always used auto plugs, no need to index with carb engines.
Good work , thanks much
Fantastic upload Stu.
Have you had a chance to test a hydrofoil yet, i"m eager to hear an honest opinion on them?
Have you had much experience with gear driven oil injection pumps over oiling or leaking from the oil seal?
Thanks mate. No, haven't done the hydrofoil yet but it is sitting in the workshop ready to go so it won't be long. I haven't seen an oil pump leaking, it is very possible, all seals fail eventually. Some are adjustable by a threaded linkage so if it is adding too much oil they can often be "turned down"
Hi Stu, how do you check spark on a face gap spark plug? In another video you had the normal spark plug connected to the cable and grounded on the outboard and as you cranked the engine we can see the spark jump from the electrode to the ground. But with a face gap version, there is no ground plate. So can we still do this simple test and would there be a spark from the electrode to the housing/thread section instead? Thanks.
Yep, you've got it. The spark will jump from the centre section to the housing.
So basically I have a 25 HP 2 stroke Mercury that came with a used boat I bought. Electric starter motor works but the engine doesn't run. Checked fuel lines, all good. Did the spark test and no spark on either of the spark plugs. Previous owner reckons it is the powerpack. Will do some more troubleshooting before I replace the powerpack.
Oh I do have a question on spark plugs. Mercury Marine service manual shows a view on spark plug conditions with my two stoke. With wet plugs after it run shows a rich burn. I know it's better to be a little rich rather than lean and running at a idle with muffs could be why? Just need you're thoughts on this. Thanks
The carb will vary its air fuel mixture through its rev range. You might be able to just lean out the idle mixture screw if it is too rich, this won't greatly affect the full throttle mixture.
Yeah man whenever I pulled my plugs while running on muffs they are always drenched in oil. I think Stu mentioned in vid to run at average speed for a while then pull n check plugs for a true result
Thanks for the conformation on the wet plugs at idle. No worries but will check again after running up mid speed for awhile.
Stu would like a few t shirts how do I order them thanks Bill
William Bates 0361 here is the link dangarmarine.com.au/collections/merchandise/products/dangar-marine-t-shirt
The shirts are actually very comfortable. And the prices are in Aus so it was cheaper when converted to US dollars.
What's the gap n a 9.5 Evinrude
As a two stoke gets older would you tend to a colder or hotter spark plug? Which is best for cold starting a cranky Johnson 85 circa 78 that runs sweet once warmed up?
I would stick with the factory recommendation. A hot plug doesn't have a hotter spark, it just gets hotter after a while of running so it won't affect your hard starting. Hard starting generally comes down to poor compression, bad reed valves, dirty carburettor or a faulty choke mechanism.
Good afternoon, I really enjoyed your videos, I'm a motor mechanic in Maceio, Alagoas, Brazil, I would like to work with you. Thank you and hug.
Thanks mate, glad you are enjoying the videos. I've never been to Brazi but I would like to go one day! :)
Hey Stu, great video. Regarding the middle numbers and the last number on a spark plug, mine uses a QL78YC what does that tell you?
Hi Serge, this is the guide to the Champion numbering system www.sparkplugs.com/Data/uploads/Charts/Champion_Numbering_System.jpg
very interesting. learned a few things
Thank you
Excellent
Thanks mate.