My bike idles ok but when i apply the rear brake it dies. I should mention that it has two screws one for the idle and one for the air/fuel mixture. By the way it is a 80 Indian moped with a keihin pa moa carburator. Thank you
@@Fixyourdirtbike I have not driven it yet i just recently completed the restoration i started it and adjusted the carburator and that is it. When i apply the brakes is when it dies. I was told that i need to do a compression check to see if the rings are ok. Right now i dont have the right adapter to do the compression check. If i remember right the manual says to adjust the idle until the rear tire stops turning but if i do that it dies so i had to raise the idle. So i am not sure if i am doing the carb adjustment correct or there is a problem with compression and it can't handle a load.
Hello , can you help me with adjustment this carburator on Yamaha DT 125, I screw and unscrew it and now not have power at start , I must add throttle more times to get power
I really hope i get an answer, So my carb does have the idle adjustment knob and ive changed it. How do i reset it to a neutral position? Just twist it all the way in? but that would probably take the idle down way too much. or take it off and then do it? Ive got it better than before but the idle still is a little bit off. Idk if im making sens haha but I Hope someone can help, thanks. Oh i almost forgot I have a 96 rm250, its in good shape for the most part.
there are very view tutorials on the web that get such a good point out so fast .a screw driver,a strong leg,and patience,could not have said it better myself.
Wow, I was ONLY adjusting the fuel mixture because I didn't know there was a pilot air screw. So my bike would fire right up but die over time because I was flooding it. It was eating gas and throwing fuel onto the exhaust. Thanks a lot.
Very helpful video. My scooter in freezing temperature was reaching easily 70kmh and with a warmer weather slowing down and I had to be satisfied with 45kmh. Now at least I understood why... Thank you very much!
Thank you so much for this video, on our RM85/L there is no idle tune like there is on the 125, I didn't know where to adjust the idle because it would just bog out and die after 3 seconds. I will definitely use this to help tune my bike. Thanks so much!
On a PWK35 there’s an air adjust screw and a throttle stop screw. The throttle stop screw is pretty straight forward but some input on the air adjust screw would be appreciated.
The throttle stop screw is for on the fly adjustment, and the air screw is for adjusting the base tune of the idle. Checkout my tuning guide for more info → www.fixyourdirtbike.com/fix/how-to/2-stroke-carb-tuning/
Thank you so much lol just bought my first 2 stroke bike 1999 cr250 (has this same carb) and couldn’t figure out why it wasn’t running right, turns out I had my af screw turned all the way in
WOW ONE OF THE BEST HELPFUL VIDEO ON YOU TUBE .. NO SHIT TALKING JUST STRAIGHT TO THE POINT AND FINISH ... WHAT I NEEDED TO KNOW ... GOOD ON YOU MATE !
I have a TM 300 with the usual PWK 38. The bike starts at the first kick, cold or warm, but it tends to stall and the air screw does nothing... I thought I had a leaky jet block gasket but after a leak test, found out it's good. 42 idle jet. 175 main. The bike runs OK, the only problem is this rough idle, the tendency to stall (dangerous, expecially when going downhill on very slow/hard situations) and the air screw doesn't affect it. The carb is clean.
I got a 98 Yz80, and sometimes when I give it full throttle it will bog, usually in the higher gears, 4-6, it idles great, and usually when I start it, I don't have to use the choke, even when cold. I'm running 50:1
You are definitely running too rich. Try reducing the size of your main jet first, that should take care of your bogging. I would reduce the size of your slow jet too, if you can start cold with no choke it's too rich.
Hey bud love the videos!! My YZ250 runs nice and crisp when it's cold out but as the weather gets warmer (Las Vegas Nevada) it's not as crisp anymore. I don't want to mess it up so i haven't tinkered with it but your video helps. I think it's running rich right now.
Thanks for watching! Yes, if your bike is crisp in the cold, but sluggish in the heat, you have a rich condition when it warms up. How drastic are the temp changes in Las Vegas?
My motorcycle stock at 9 years and when it cleaned the carb only it start but I can't reach 60kmh cause of "bogging" or anything and they said it's too old so that can't run , I hope this work hehe.. : Thank you for fast guiding♥️
The air screw can only be turned by screw driver the idle screw is usually protruding out with a spring under it that you can see. SO yes there is an idle screw and an air screw. In this video the idle screw was actually the choke knob but not all carbs are that way. if turning your choke knob does not adjust idle you will see an additional screw that protrudes out usually can grab by the finger and turn it or a flay head. Then the air screw is counter sunk into the carb only a screw driver will reach it. The idle screw lifts the carburetor slide to let more air in.
terry fonz That is the throttle stop screw. There is no fuel adjustment, that's what the idle air screw Is for. It adjusts the flow or air into the carburetor to match the flow of fuel from the pilot jet, also knows as the slow jet.
Josko Wrabec Set your throttle stop screw all the way out so the throttle plate is closed. Set your idle air screw to a neurtal position. Try to start your bike. If it starts and has a very high idle (more than the idle screw can compensate for), your jetting is too lean - go up a jet size and try again. If you can't get your bike started, pull the spark plug. If it's wet with fuel, your jetting is too rich - go down a jet size and try again.
Sounds like an air leak from around the carb seat or reed valve seat. Check to see if there’s any air coming out from around those areas. If not, check the torque on your head bolts or your head gasket.
I just bought a 93 CR125 and it idled alright. Since then I replaced the dented pipe with a FMF one and cleaned the carb as it was dirty. It starts easily but won't idle at all and the idle adjustments screw doesn't change the idle.
Double check that your carb boots are sealed and the air filter is installed and clean. Just to be safe, if you haven't already, I would go through the entire fuel/air system and make sure everything is clean and in good shape. Fuel filter, air filter, reed valve, carb boots etc. Let em know if you find anything, if you cant get it to idle message me on my FB page and we'll figure this out. facebook.com/FixYourDirtBike
Fix Your Dirt Bike thanks buddy. Yeah I strip the whole bike down clean the whole airbox so clean the air filter it's as clean as it was when it was new. I just changed the reeds to Boyesen as well and still no change. The FMF sheet says to change my main, pilot jet and needle.
Does the FMF sheet say specifically what pilot jet and needle to use? Or does it just say increase fuel flow? Either way, I'd start with a one size larger pilot jet and raise the needle by one position and see what you get. At this point small adjustments are key!
Fix Your Dirt Bike it says to use a 172 main and a 58 pilot. The clip position stays stock and the air screw 1.5 turns out. I was told yesterday at the dealer that I bought the pilot jet at that it will not affect the idle at all and that the carburetter has to be dirty still so I will take it apart yet again and make sure every orifice is clean then try it again. I bought a 58 pilot jet which I'll swap as I do t want it to run too lean. I'll let you know what happens.
Who said that? The pilot jet directly effects idle. Anyway, I can't count how many times I've cleaned a carb only to have the pilot clog when I get to the trails. Every time it's something that was knocked loose during cleaning but didn't make it out of the carb. hHave you checked your float clearance? You may have accidentally bent the float tab and it's not letting the bowl fill all the way.
My kx125 revs pretty high on idle and when I rev it, it revs up good but will be idling a little higher than it was before. If I rev it up high, it idles extremely high too
Thank you so much. Rebuilt my cr 125 couldn't figure out how to fix the idle cuz it idled at almost the rev limiter knew it was carb related thanks to the video I know how to fix it
This video is very helpful and spot on! Why we should turn the pilot screw all the way out before turn it all the way in and adjust it? My rmx 250s runs with a keihin pwm 36. It won't idle and adjusting the pilot screw does nothing at all. I tried 48, 40, 38 and 35 jets. Runs better with the 35 but still bogging and cutting off when I leave the throttle. Should I go for a smaller jet? Thanks!
Turning the idle screw in and out lets you count the turns so you can reset it to neutral. What kind of bog? Is it a chug chug or a bwwwaaahhhh sound? Here's my tuning guide too → bit.ly/2tidladjstmnt
Took it apart today. I think I found the problem. It s the oring under the jets body that was leaking.. check this out ruclips.net/video/iwKpSmb9iOU/видео.html
@@Fixyourdirtbike just ordered the oring. I have to wait a few days for it as it's coming from Holland to me here in Greece. I will let you know for the progress as soon as I get it. Thanks again for your help and your replies!
Bro u fixxed my stupid gas gas 250 it was 4 stroking bad and bi mechanic was able to fix it had to to down from a 180 to 160 and main jet was a 50 and went to a 45 bc it kept fouling plugs also 1-2 gear would feel like hitting rev limiter thank you so much
Great video. My son has Suzuki jr 80. We just had the carb worked on and it's running great, but he now has a hard time starting it. He's 9 and weighs 65 lbs and has a hard time kicking it hard enough to get it started. I can start it pretty easy when I choke it and kick it over, but he struggles where it used to be really easy for him. After it's warmed up he can start it fine. Would this be an air adjustment?
If the temperature increased significantly where you ride your carb is now running rich. Play with the air screw and see what happens. You may need to re-jet a size smaller on both slow and main.
Love the video...so I have a 1978 Suzuki 125ts with mikuni vm24 carb. One main screw on right side middle, one small screw on left side closer to air filter...I have done every adjustment possible, it will idle until I ride it and try to coast or downshift then it dies...any suggestions
Thanks! The bigger screw on the right side is the throttle stop screw, so the more you screw that in, the higher the throttle slide will sit when closed. The small screw on the left is your air screw which affects the air/fuel mix at idle. First things first; when did you clean your carb last?
I'm new to bikes and have a 1967 Yamaha ym2c 2 stroke, it takes a couple of kicks to get started but immediately shoots up to redlining on the RPM's, what would be the best course of action here? Any help is appreciated
Mike Heide This is caused when the air fuel mix is too lean. This can be caused by jetting or bad seals/gaskets. When was the last time you cleaned your carb?
Mike Heide Install your exhaust and try again. You also may want to check your new gaskets and re-torque everything. A vacuum leak will cause take off too.
does anyone know where to adjust the float level on keihin pj28L is it like adjusting any other float, from the base of the carb to the top of the float or is it different?
Hello, I enjoyed watching it, but I have a Kawasaki KX100 bike. There is no change when moving the air adjustment screw, knowing that in the past the adjustment changes. What are the possible reasons?
Thanks for the great information I have a scooter if i but the fiter in place it wont go faster because it nees more air to go in what the cause of that... And the curb dont have a air screw but the thing i know it have a big jet hole...
Hey quick question I have CR250R she idles when air screw is all the way out but don’t when the air screw is closed ? Would you reckon I need a new smaller jet? Thank you
Hey there thanks for the video, i hope u can help me out , i just got a ktm exc-r 450 and i want to know what does the idle helps in exactly? and what the best thing to do? also am facing an issue when i turn the throttle to speed up sometimes i feel like the bike doesn't respond well as it feels like its about to die or its like its out of gaz then it speeds up?
I got a keihin pwk 28 carb that has been modified by the previous owner... he took the choke off and filled the choke passages with jb weld so basically carb has no choke is that bad or a good thing??
How do you re set the idle adjustment knob ? My cr want ideal IV had the bike for year and never had a proper IV clean carby and new plug and still want ideal. I did take the idle screw with the lock nut out when I was cleaning it and forgot how many turns can you please tell me how many ruffly in it should be
The throttle stop screw should be adjusted after you get your low idle set. The throttle stop screw does not change the mix in the idle system, because it holds open the throttle plate, which engages the main jet system. I'll set my throttle stop (if I'm on a bike that has one) when riding in difficult conditions like big rocks or technical hill climbs to make the throttle a little more responsive. Another benefit is it's easier to keep your bike alive when you get stuck/crash.
94 WR250Z Yamaha 38mm air striker 6910ft altitude, FMF pipe and a 70 pilot. Bike idles but bogs on revving, runs better with choke on and new carb everything’s clean and flowing. Seems to get better with bigger pilots and the air screw is finally helping as the pilots get bigger. ????????????????????? Please and thank you. 😃😃
My problem is not the start it starts by barly even trying even before the new rings but my problem is that i fould like 10 sparks plug in May like i would ride it one day with a new spark plug and next day it would fall so i put new after new it wasnt annoying at first but last week i went riding and i fouled 2 spark plugs it was fill with oil is this the problem?
Either your mix is too rich, you are idling to much, or both. How do you ride? Woods or MX? 2 strokes need to be under load keep oil flowing through the engine. so If you find yourself idling a lot or riding to slow you will see plug problems, and rich jetting will make it worse.
Also, are you using the same model of plug every time? Is it the OEM plug? If you are using a plug that is not designed for the ignition system, you may be getting a colder spark than you need. If you are using the OEM plug, your ignition system might be failing.
Hi, thanks for all your videos. Would you believe my air adj screw is totally seized. My carb is a 38 PWK Shorty off a 2007 exc. I will need to drill it out. Unbelievable !
My bike has a hanging idle upon start it revs out to full throttle carb isn’t stuck open or seized brand new car just installed I’m thinking air leak also it’s a 2 stroke cr250r
thank you for video,I have problem with carburetor,when engine is cold I close completely choke shutter and engine work idle,but after warming when I open choke shutter engine works high,max rpm and after few seconds engine falls !! can you solve this problem please?
It sounds like your jetting is too lean and too much air is getting through. When you are choked your engine is getting the right ratio so it runs right, then when it opens the sudden increase in oxygen causes the engine to take off. I would start with a larger slow jet.
I have a 1996 yz125 and it is bogging alot. If u don't let out the clutch super slow it stalls, it sputters also. I live in Colorado at high altitude so that may be some of the problems. It is about 40 to 60 degrees Fahrenheit right now when I ride, what jet should I run,
Great video, but I have a quick question. When you say to set your idle adjustment knob to a neutral position, what do you mean? I have a 1997 CR125R and the carb looks just like this one. It basically looks like you've turned the idle adjustment knob all the way in. Is that what you did? If I do that my bike will die, but that's OK because this will just be the starting point and then I will use the air screw and jets to correct the idle.
+mrkevelev When I say a neutral position, turn the idle in all the way, then unscrew it counting the turns until it stops or unthreads. Then turn it back in half way = neutral.
Thank you for the video. I have a Keihin 38 PWK and the air mixture screw has to turn almost all the way out in and the idle adjustment screw has to turn almost %70 in in order to have a smooth idle. I put pilot Jet 45 on it (the stock size is 48) and no improvement. What would you suggest? I appreciate your help. Ejmin
My 92 lt250r won't idle with just mixture screw have to use throttle to keep running started at 48 piolet jet now on 40 jet still won't idle do I go lower?
Hello I have a Gas Gas Ec 250, I have problems with the idle, when it's cold runs good, after I warm it up don't idle. It starts good however without the choke of the first try. The second problem is the fuel consumption I think is too much with a full gas tank ( around 9.5 litres ) I run 50 km. My question is: how turns must be the air/mixture screw to obtain the best results, and not cause damage to the engine (carb is Keihin PWK 38mm). Thanks.
Is sounds like your running rich. The temperature of the engine effects the incoming air, so a cold engine will cool the air, making it more dense. That's why you can start without choke but can't idle. I would drop down a size on your jetting and see what you get. How old is your bike? If you're going through more fuel than you should, it is most likely bad reed valves.
The year of the bike is 1999, I appreciate your help, I will check the reeds tomorrow. If you know any other informations about this bike (carb settings or other) please let it there.
Hello there, I just bought a 1993 Yamaha Yz250. I cleaned the carb and noticed that it has a 360 main jet and 45 pilot. Can I put a 250(for example) main jet to cut the extreme power that it has, a little bit? Is this harmful for the cylinder, piston, rings and others? The carb is Mikuni TM38 Thanks for reply.
Do not run your bike lean, that's how you kill an engine. Just take it easy, keep your clutch covered, and you will get used to the power before you know it!
My 50cc 2 stroke scooter idle god in place take off good but in take off its going like 3-4 seconds good then the rpm drop and after that if you give half or whole throtle its not going streight it hessitate and after 4-5 seconds its going crazy after full throtle. The transmision is all new rollers are 5.0 gram it was pull nicly until i change the piston and cilynder then i have this problem what you think
What does he mean by placing the adjustment choke knob to a nuetral position? Do you mean half way? I have both Clymer and Honda repair manuals and both books do not have a direct answer for this on the cr125. I have read 7 clicks out and/or 30 clicks out but 30 clicks and that is with the choke fully on so there is a lot of conflicting information.
1993 cr125. It's cranking and idling fine. But 1st through 3rd the power bands are cutting out at top peak. 4th and 5th it's hitting just right. On take off it's sluggish. Powerbands take too long to kick in. I'm not any good what so ever at carburetor adjustment. Where it's at now is the best I can get it.
@@Fixyourdirtbike I messed with it and got it pretty close. But I noticed the power valves are not working on low RPMs. Powerbands are on the pipe only. I'm trying figure how to adjust the power valves to come in a little early.
@@Fixyourdirtbike I got a question, can the power valves arm come loose? I took the cover off the left side because I didn't want to take the pipe off unless I had to. And I cranked it up and the valve didn't move reviving it up. Or can I determine anything that way?
first it fouled while ideling then I put a new plug in and it lasted one tank.then the next day I started it idled fine then I rode like 100 yards and it fouled out while riding.i took it out and its wet and dark and will not spark anymore.
Hello I've been watching your video trying to tune a 96 ds80 just put this in the rings in bike is running and runs good but dies after 10 15 minutes have gone through the car and adjusted the flow also clean the car but it was very clean do you have any ideas that I may try?
I have Yamaha 125Z catalyzer... I just changed carb to UMA 30 but it make unstable sound from exhaust... Should i modify block and piston little bit big...? Or make some change in hole of air on block..?
You shouldn't need to modify anything past the reed valves. It just sounds like your air/fuel mixture isn't tuned right. What carb did you have on it before the UMA 30?
Ok. 2mm Isn't going to make a huge difference, but if you want to get more power you will need to upgrade everything in the air/fuel and exhaust system. You would need to get a performance exhaust system to match your new carb to see a difference.
Wassup my KTM 250 2 stroke is acting up so when I ride it and try going on 4 gear it slowly turns of by itself and sometimes when i barley turn it on and put it on first gear then on second gear the throttle goes on it’s own with out me even giving it gas what do you think is wrong if you can help me out I would truly appreciate it
Bogging and taking off, that's interesting. When was the last time you cleaned your carb? Have you changed elevation or has the temperature changed significantly before you started having issues? When was the last time you checked your reeds?
what's up man just built a water-cooled motor.motor runs and idle but when I throttle it bogs but if I run choke up it response like how it should be if it's down. running a 33 Keihin carb main-142 pilot-52 needle clip one up from the middle. but question is way does it bog? I'm assuming it's my pilot to small??? I'm like 2 & 1/2 turn out on pilot screw from the body.lmk thanks
Hey man I have a 2000 cr125 and I rode it a week ago and it ran like a champ. I kick start it today a week from last time i rode it and it kicks over first kick but wont idle. If i let off the throttle it immediately dies. Any tips?
It sounds like your idle circuits are gummed up or your plug is fouled enough to still run but not idle. Check the plug first, and if that's clean you'll need to clean your carb.
@@Fixyourdirtbike Thank you so much man. Appreciate getting back with me! Gonna grab a new plug this weekend and throw that in and see if thats it first. I'll let you know how it goes!
Hi! My bike starts, goes ok on idle (maybe a lil too high) but when i give throttle the gas hangs for a bit and slowly goes down, I dont think i have it too lean. Anything i can do to fix??
Checkout more *How-To* guides here! → goo.gl/EwdtM4
My bike idles ok but when i apply the rear brake it dies. I should mention that it has two screws one for the idle and one for the air/fuel mixture. By the way it is a 80 Indian moped with a keihin pa moa carburator.
Thank you
@@SDsailor7 When you hit the brake, or come to a stop in general?
@@Fixyourdirtbike I have not driven it yet i just recently completed the restoration i started it and adjusted the carburator and that is it. When i apply the brakes is when it dies. I was told that i need to do a compression check to see if the rings are ok. Right now i dont have the right adapter to do the compression check. If i remember right the manual says to adjust the idle until the rear tire stops turning but if i do that it dies so i had to raise the idle.
So i am not sure if i am doing the carb adjustment correct or there is a problem with compression and it can't handle a load.
Hello , can you help me with adjustment this carburator on Yamaha DT 125, I screw and unscrew it and now not have power at start , I must add throttle more times to get power
I really hope i get an answer, So my carb does have the idle adjustment knob and ive changed it. How do i reset it to a neutral position? Just twist it all the way in? but that would probably take the idle down way too much. or take it off and then do it? Ive got it better than before but the idle still is a little bit off. Idk if im making sens haha but I Hope someone can help, thanks.
Oh i almost forgot I have a 96 rm250, its in good shape for the most part.
This was the most time - efficient video i have seen in my life.
Besides the unskippable add at the start lol
It was perfect.
Hell ya
@@SimplyMage19 get RUclips red if u don’t want adds
I was Going to say that same thing
Quick and to the point with no BS, I like it!
there are very view tutorials on the web that get such a good point out so fast .a screw driver,a strong leg,and patience,could not have said it better myself.
Wow, I was ONLY adjusting the fuel mixture because I didn't know there was a pilot air screw. So my bike would fire right up but die over time because I was flooding it. It was eating gas and throwing fuel onto the exhaust. Thanks a lot.
I'm 4 years late but, thank you. Made my life way easier. I was adjusting the choke idle knob haha.
Me too
They say the more simple an explanation, the more understood the subject is. This was so quick and to the point, THANK YOU!!!
NAILED IT!! No fluff and all resolve.. KILLER!!!
Very helpful video.
My scooter in freezing temperature was reaching easily 70kmh and with a warmer weather slowing down and I had to be satisfied with 45kmh. Now at least I understood why...
Thank you very much!
Hey man, I appreciate the video I’m 14 and I have to do everything myself and this is my first time ever doing this and I did it first try thank you
Bravo! this is a master class on how to make a quick and informative video. Bike is idling like a champ now.
7yrs but i used ur video as guide thank you
Thank you so much for this video, on our RM85/L there is no idle tune like there is on the 125, I didn't know where to adjust the idle because it would just bog out and die after 3 seconds. I will definitely use this to help tune my bike. Thanks so much!
Thomas Harp Glad to help!
Thank you for the quick tutorial!! My IT175 was idling super high and this did the trick. Took less than 5 minutes to adjust it properly. Thank you!!!
Glad to help!
On a PWK35 there’s an air adjust screw and a throttle stop screw. The throttle stop screw is pretty straight forward but some input on the air adjust screw would be appreciated.
The throttle stop screw is for on the fly adjustment, and the air screw is for adjusting the base tune of the idle. Checkout my tuning guide for more info → www.fixyourdirtbike.com/fix/how-to/2-stroke-carb-tuning/
Just got my fist 2 stroke and im new to the jetting carburetors. Thanks this vid helped alot
Fantastic video. 1 minute 47 seconds and all the information I needed. Keep up the good work!
Awesome video. Easiest to follow and very very informative. I thank people like you that make it easy .
This video just solved all my issues in 2 minutes. Thank you
Thank you so much lol just bought my first 2 stroke bike 1999 cr250 (has this same carb) and couldn’t figure out why it wasn’t running right, turns out I had my af screw turned all the way in
I am 5 years late but THANK YOU SO MUCH. I will try this as soon as I can!!!
Since I bought the engine kit I’ve never touched or took apart the carb the only thing I have the touched is the set screw with spring
This video was so informative and straight forward that I felt stupid for not understanding carburetors beforehand!
HAHA, thanks for watching!
Helped me start my bike after a top end rebuild 🙏🏼 thank you!
WOW ONE OF THE BEST HELPFUL VIDEO ON YOU TUBE .. NO SHIT TALKING JUST STRAIGHT TO THE POINT AND FINISH ... WHAT I NEEDED
TO KNOW ... GOOD ON YOU MATE !
Thanks for the video i built a 2 stroke again its been long enough to almost forget the air leaks and mostly the simple things 😂😅
I have a TM 300 with the usual PWK 38. The bike starts at the first kick, cold or warm, but it tends to stall and the air screw does nothing... I thought I had a leaky jet block gasket but after a leak test, found out it's good. 42 idle jet. 175 main. The bike runs OK, the only problem is this rough idle, the tendency to stall (dangerous, expecially when going downhill on very slow/hard situations) and the air screw doesn't affect it. The carb is clean.
8 years later and this video is still the best.
Concise, precise and straight to the point. Gotta love it.
my plugs are wet and dark. what should I try first?
take air screw out 1 turn or more
I got a 98 Yz80, and sometimes when I give it full throttle it will bog, usually in the higher gears, 4-6, it idles great, and usually when I start it, I don't have to use the choke, even when cold. I'm running 50:1
You are definitely running too rich. Try reducing the size of your main jet first, that should take care of your bogging. I would reduce the size of your slow jet too, if you can start cold with no choke it's too rich.
Hey bud love the videos!! My YZ250 runs nice and crisp when it's cold out but as the weather gets warmer (Las Vegas Nevada) it's not as crisp anymore. I don't want to mess it up so i haven't tinkered with it but your video helps. I think it's running rich right now.
Thanks for watching! Yes, if your bike is crisp in the cold, but sluggish in the heat, you have a rich condition when it warms up. How drastic are the temp changes in Las Vegas?
My motorcycle stock at 9 years and when it cleaned the carb only it start but I can't reach 60kmh cause of "bogging" or anything and they said it's too old so that can't run , I hope this work hehe..
: Thank you for fast guiding♥️
It sounds like a vacuum leak. Check your carb body for cracks and recheck all the seals.
What about the idle screw? What should it be set to when your adjusting the air screw?
Josko Wrabec What bike are you working on? Your idle screw is the air screw.
The air screw can only be turned by screw driver the idle screw is usually protruding out with a spring under it that you can see. SO yes there is an idle screw and an air screw. In this video the idle screw was actually the choke knob but not all carbs are that way. if turning your choke knob does not adjust idle you will see an additional screw that protrudes out usually can grab by the finger and turn it or a flay head. Then the air screw is counter sunk into the carb only a screw driver will reach it. The idle screw lifts the carburetor slide to let more air in.
terry fonz, so which one do I adjust first? And what baseline should I start off with?
terry fonz That is the throttle stop screw. There is no fuel adjustment, that's what the idle air screw Is for. It adjusts the flow or air into the carburetor to match the flow of fuel from the pilot jet, also knows as the slow jet.
Josko Wrabec Set your throttle stop screw all the way out so the throttle plate is closed. Set your idle air screw to a neurtal position. Try to start your bike. If it starts and has a very high idle (more than the idle screw can compensate for), your jetting is too lean - go up a jet size and try again.
If you can't get your bike started, pull the spark plug. If it's wet with fuel, your jetting is too rich - go down a jet size and try again.
I have a 05 ktm85 sx and every time I start the bike it jus opens wide up and idles as high as possible what should I do?
im having same problem w 86 it200
Sounds like an air leak from around the carb seat or reed valve seat. Check to see if there’s any air coming out from around those areas. If not, check the torque on your head bolts or your head gasket.
I had the same problem with my 04, it’s the left crank seal
I just bought a 93 CR125 and it idled alright. Since then I replaced the dented pipe with a FMF one and cleaned the carb as it was dirty. It starts easily but won't idle at all and the idle adjustments screw doesn't change the idle.
Double check that your carb boots are sealed and the air filter is installed and clean. Just to be safe, if you haven't already, I would go through the entire fuel/air system and make sure everything is clean and in good shape. Fuel filter, air filter, reed valve, carb boots etc. Let em know if you find anything, if you cant get it to idle message me on my FB page and we'll figure this out. facebook.com/FixYourDirtBike
Fix Your Dirt Bike thanks buddy. Yeah I strip the whole bike down clean the whole airbox so clean the air filter it's as clean as it was when it was new. I just changed the reeds to Boyesen as well and still no change. The FMF sheet says to change my main, pilot jet and needle.
Does the FMF sheet say specifically what pilot jet and needle to use? Or does it just say increase fuel flow? Either way, I'd start with a one size larger pilot jet and raise the needle by one position and see what you get. At this point small adjustments are key!
Fix Your Dirt Bike it says to use a 172 main and a 58 pilot. The clip position stays stock and the air screw 1.5 turns out. I was told yesterday at the dealer that I bought the pilot jet at that it will not affect the idle at all and that the carburetter has to be dirty still so I will take it apart yet again and make sure every orifice is clean then try it again. I bought a 58 pilot jet which I'll swap as I do t want it to run too lean. I'll let you know what happens.
Who said that? The pilot jet directly effects idle. Anyway, I can't count how many times I've cleaned a carb only to have the pilot clog when I get to the trails. Every time it's something that was knocked loose during cleaning but didn't make it out of the carb. hHave you checked your float clearance? You may have accidentally bent the float tab and it's not letting the bowl fill all the way.
How do you reset the idle knob? Do you just close it all the way or the same as you did to the air screw?
I have a 99 cr 250 and your videos have help so much thanks very much.
Glad to hear!
Me too.. super amount of help!!
And my 1999 cr250 is doing much better..
My kx125 revs pretty high on idle and when I rev it, it revs up good but will be idling a little higher than it was before. If I rev it up high, it idles extremely high too
It sounds like your slide or throttle cable is sticking
Thank you so much. Rebuilt my cr 125 couldn't figure out how to fix the idle cuz it idled at almost the rev limiter knew it was carb related thanks to the video I know how to fix it
Cam Ben Glad I could help!
The idle adjustment know on the choke, how do u reset it back to neutral position? Or how many turns clockwise or counterclockwise?
Yeah I want to know the same thing...
nice vid man.now i can easily start my scooter after watching your video i feel like im the king of the world.lol
more vid to come
This video is very helpful and spot on! Why we should turn the pilot screw all the way out before turn it all the way in and adjust it? My rmx 250s runs with a keihin pwm 36. It won't idle and adjusting the pilot screw does nothing at all. I tried 48, 40, 38 and 35 jets. Runs better with the 35 but still bogging and cutting off when I leave the throttle. Should I go for a smaller jet? Thanks!
Turning the idle screw in and out lets you count the turns so you can reset it to neutral. What kind of bog? Is it a chug chug or a bwwwaaahhhh sound? Here's my tuning guide too → bit.ly/2tidladjstmnt
Thanks for the reply. This is what it is doing. ruclips.net/video/u-sTVQot_uY/видео.html When I let the throttle dies...
Took it apart today. I think I found the problem. It s the oring under the jets body that was leaking.. check this out
ruclips.net/video/iwKpSmb9iOU/видео.html
Oh yeah, that definitely doesn't help. Where able to fix and test it yet ?
@@Fixyourdirtbike just ordered the oring. I have to wait a few days for it as it's coming from Holland to me here in Greece. I will let you know for the progress as soon as I get it. Thanks again for your help and your replies!
Bro u fixxed my stupid gas gas 250 it was 4 stroking bad and bi mechanic was able to fix it had to to down from a 180 to 160 and main jet was a 50 and went to a 45 bc it kept fouling plugs also 1-2 gear would feel like hitting rev limiter thank you so much
Question, when you try to start your bike the first time with the screw halfway out, are you using choke and is the engine cold?
The engine should be warm when tuning. I should have put that in there, and I have plans to redo this video.
Great video. My son has Suzuki jr 80. We just had the carb worked on and it's running great, but he now has a hard time starting it. He's 9 and weighs 65 lbs and has a hard time kicking it hard enough to get it started. I can start it pretty easy when I choke it and kick it over, but he struggles where it used to be really easy for him. After it's warmed up he can start it fine. Would this be an air adjustment?
If the temperature increased significantly where you ride your carb is now running rich. Play with the air screw and see what happens. You may need to re-jet a size smaller on both slow and main.
How do you set the idle adjustment knob to a neutral position? like halfway in between when you begin adjusting the air screw?
Yes, the same way you neutral the air screw.
Fix Your Dirt Bike thank you so much. You earned a subscriber.
Thank you carburetor man very informative very professional very well done😊
Thank you RUclips viewer. 😀
Love the video...so I have a 1978 Suzuki 125ts with mikuni vm24 carb. One main screw on right side middle, one small screw on left side closer to air filter...I have done every adjustment possible, it will idle until I ride it and try to coast or downshift then it dies...any suggestions
Thanks! The bigger screw on the right side is the throttle stop screw, so the more you screw that in, the higher the throttle slide will sit when closed. The small screw on the left is your air screw which affects the air/fuel mix at idle.
First things first; when did you clean your carb last?
Solid video i will try this on my bike tomorrow
Good luck!
Best ever, beats the hell out of the 20 min junk.
I'm new to bikes and have a 1967 Yamaha ym2c 2 stroke, it takes a couple of kicks to get started but immediately shoots up to redlining on the RPM's, what would be the best course of action here? Any help is appreciated
Mike Heide This is caused when the air fuel mix is too lean. This can be caused by jetting or bad seals/gaskets. When was the last time you cleaned your carb?
Mike Heide Install your exhaust and try again. You also may want to check your new gaskets and re-torque everything. A vacuum leak will cause take off too.
does anyone know where to adjust the float level on keihin pj28L is it like adjusting any other float, from the base of the carb to the top of the float or is it different?
Pilot air screw refers to al the screws on the carb or just one?
Just the one underneath the intake.
@@Fixyourdirtbike thank you
Great video! Bike won’t idle any recommends on where to buy the stock keys including the slow jet?
My kids bikes idles to the moon n neutral, then when u put it in gear it bogs n almost dies what can cause this
Your clutch might be making friction
What does it mean when I have oil coming out my silencer. All settings are from factory. 23 yz125. 32:1
White smoke antifreeze, gray smoke oil.. from your transmission.. crank seal failure..
Should be the same idea for a snowmobile right? Since they're both 2 stroke engines
Yes
Hello, I enjoyed watching it, but I have a Kawasaki KX100 bike. There is no change when moving the air adjustment screw, knowing that in the past the adjustment changes. What are the possible reasons?
Thanks for the great information
I have a scooter if i but the fiter in place it wont go faster because it nees more air to go in what the cause of that... And the curb dont have a air screw but the thing i know it have a big jet hole...
The ratio is correct with the air filter on. So the engine gets enough oxygen and fuel to work right.
You know how the back wheel spins when given throttle on the stand is that a good sign that the bike is tuned better?
That dosen't tell you much because the engine isn't under load.
@@Fixyourdirtbike so go ride it tommorow with a fresh plug and see how it checks out then?
Yes
Hey quick question I have CR250R she idles when air screw is all the way out but don’t when the air screw is closed ? Would you reckon I need a new smaller jet? Thank you
I would check your float level and float valve seat first. If those are OK, then you would need a smaller slow jet.
Hey there thanks for the video, i hope u can help me out , i just got a ktm exc-r 450 and i want to know what does the idle helps in exactly? and what the best thing to do? also am facing an issue when i turn the throttle to speed up sometimes i feel like the bike doesn't respond well as it feels like its about to die or its like its out of gaz then it speeds up?
I followed your instructions and my bike still doesn't start but it gets so close but still doesn't. do you think I need new jets?
lol thanks. Finally dialed in my KDX
Exactly what I needed to hear and nothing else, thank you!
I got a keihin pwk 28 carb that has been modified by the previous owner... he took the choke off and filled the choke passages with jb weld so basically carb has no choke is that bad or a good thing??
93 yz not starting. i guess i should go with the stock yamaha carburetor settings, would yo agree?
How do you re set the idle adjustment knob ? My cr want ideal IV had the bike for year and never had a proper IV clean carby and new plug and still want ideal. I did take the idle screw with the lock nut out when I was cleaning it and forgot how many turns can you please tell me how many ruffly in it should be
Also dose the throttle stop screw serve the same purpose as the idle adjustment knob?
The throttle stop screw should be adjusted after you get your low idle set. The throttle stop screw does not change the mix in the idle system, because it holds open the throttle plate, which engages the main jet system. I'll set my throttle stop (if I'm on a bike that has one) when riding in difficult conditions like big rocks or technical hill climbs to make the throttle a little more responsive. Another benefit is it's easier to keep your bike alive when you get stuck/crash.
94 WR250Z Yamaha 38mm air striker 6910ft altitude, FMF pipe and a 70 pilot. Bike idles but bogs on revving, runs better with choke on and new carb everything’s clean and flowing. Seems to get better with bigger pilots and the air screw is finally helping as the pilots get bigger. ????????????????????? Please and thank you. 😃😃
It sounds like you're running too lean. What does your spark plug look like after riding?
Fix Your Dirt Bike plugs looks pretty lean IMO, it’s just crazy to think I need big jets at this altitude. Thanks.
My problem is not the start it starts by barly even trying even before the new rings but my problem is that i fould like 10 sparks plug in May like i would ride it one day with a new spark plug and next day it would fall so i put new after new it wasnt annoying at first but last week i went riding and i fouled 2 spark plugs it was fill with oil is this the problem?
Either your mix is too rich, you are idling to much, or both. How do you ride? Woods or MX? 2 strokes need to be under load keep oil flowing through the engine. so If you find yourself idling a lot or riding to slow you will see plug problems, and rich jetting will make it worse.
Also, are you using the same model of plug every time? Is it the OEM plug? If you are using a plug that is not designed for the ignition system, you may be getting a colder spark than you need. If you are using the OEM plug, your ignition system might be failing.
I need to replace my idle adjustment knob. What is a "neutral position"
Bottom out the adjuster - count the turns as you unscrew - turn in to half that number = neutral
Hi, thanks for all your videos. Would you believe my air adj screw is totally seized. My carb is a 38 PWK Shorty off a 2007 exc. I will need to drill it out. Unbelievable !
Wow, that's a new one for me!
My bike has a hanging idle upon start it revs out to full throttle carb isn’t stuck open or seized brand new car just installed I’m thinking air leak also it’s a 2 stroke cr250r
That sounds like a vacuum leak, check your boot for cracks.
thank you for video,I have problem with carburetor,when engine is cold I close completely choke shutter and engine work idle,but after warming when I open choke shutter engine works high,max rpm and after few seconds engine falls !! can you solve this problem please?
It sounds like your jetting is too lean and too much air is getting through. When you are choked your engine is getting the right ratio so it runs right, then when it opens the sudden increase in oxygen causes the engine to take off. I would start with a larger slow jet.
I have a 1996 yz125 and it is bogging alot. If u don't let out the clutch super slow it stalls, it sputters also. I live in Colorado at high altitude so that may be some of the problems. It is about 40 to 60 degrees Fahrenheit right now when I ride, what jet should I run,
It sounds like your jetting is super rich. Drop your main jet 2 sizes and raise the clip position on the needle one notch, and see what happens.
my bike idles bad when the air screw is all the way in. do I need new jets? also, should i adjust float height as well?
It sounds like the pilot jet or idle circuit is obstructed.
Great video, but I have a quick question. When you say to set your idle adjustment knob to a neutral position, what do you mean? I have a 1997 CR125R and the carb looks just like this one. It basically looks like you've turned the idle adjustment knob all the way in. Is that what you did? If I do that my bike will die, but that's OK because this will just be the starting point and then I will use the air screw and jets to correct the idle.
+mrkevelev When I say a neutral position, turn the idle in all the way, then unscrew it counting the turns until it stops or unthreads. Then turn it back in half way = neutral.
+Fix Your Dirt Bike You do that for both the idle air screw and the idle adjustment knob?
+mrkevelev Yes, but leave the idle adjustment knob at neutral when tuning because it's for on the fly adjustments.
my bike has 2 screws on both sides of carburetor. how to know which is pilot screw?
The pilot screw is usually on the left, the slide stop screw is usually on the right.
I know its old video but should that idle adjustment knob be turned all the way in or should there be some turns left?
The idle knob / throttle stop screw should be backed out enough to allow the slide to close completely.
@@Fixyourdirtbike ok. I have same carb as in the video and it doesnt idle at all. so what could be problem? I have cleaned pilot jet.
Oh ok. When was the last time your did a full rebuild and clean on your carb?
@@Fixyourdirtbike just day ago
Was your carb working before the rebuild? How long have you had the problem?
My carb has a throttle stop screw what is that used for? Do I only use the pilot screw for adjusting idle?
Yes, only use the pilot air screw to adjust the idle.
Thank you for the video. I have a Keihin 38 PWK and the air mixture screw has to turn almost all the way out in and the idle adjustment screw has to turn almost %70 in in order to have a smooth idle. I put pilot Jet 45 on it (the stock size is 48) and no improvement. What would you suggest? I appreciate your help.
Ejmin
All I needed to know thanks man
I meant piston and rings also have adjusted the float in the carburetor will run for 10-15 minutes and then dies animal always start with choke on
My 92 lt250r won't idle with just mixture screw have to use throttle to keep running started at 48 piolet jet now on 40 jet still won't idle do I go lower?
Have you checked your reeds? I what's the temperature where you are? Have you checked your carb body for cracks? what does your spark plug look like?
Hello I have a Gas Gas Ec 250, I have problems with the idle, when it's cold runs good, after I warm it up don't idle. It starts good however without the choke of the first try.
The second problem is the fuel consumption I think is too much with a full gas tank ( around 9.5 litres ) I run 50 km.
My question is: how turns must be the air/mixture screw to obtain the best results, and not cause damage to the engine (carb is Keihin PWK 38mm). Thanks.
Is sounds like your running rich. The temperature of the engine effects the incoming air, so a cold engine will cool the air, making it more dense. That's why you can start without choke but can't idle. I would drop down a size on your jetting and see what you get. How old is your bike? If you're going through more fuel than you should, it is most likely bad reed valves.
The year of the bike is 1999, I appreciate your help, I will check the reeds tomorrow. If you know any other informations about this bike (carb settings or other) please let it there.
Hello there,
I just bought a 1993 Yamaha Yz250. I cleaned the carb and noticed that it has a 360 main jet and 45 pilot. Can I put a 250(for example) main jet to cut the extreme power that it has, a little bit? Is this harmful for the cylinder, piston, rings and others? The carb is Mikuni TM38
Thanks for reply.
Do not run your bike lean, that's how you kill an engine. Just take it easy, keep your clutch covered, and you will get used to the power before you know it!
@@Fixyourdirtbike thanks a lot for your quick reply.
My 50cc 2 stroke scooter idle god in place take off good but in take off its going like 3-4 seconds good then the rpm drop and after that if you give half or whole throtle its not going streight it hessitate and after 4-5 seconds its going crazy after full throtle. The transmision is all new rollers are 5.0 gram it was pull nicly until i change the piston and cilynder then i have this problem what you think
What does he mean by placing the adjustment choke knob to a nuetral position? Do you mean half way? I have both Clymer and Honda repair manuals and both books do not have a direct answer for this on the cr125. I have read 7 clicks out and/or 30 clicks out but 30 clicks and that is with the choke fully on so there is a lot of conflicting information.
1993 cr125. It's cranking and idling fine. But 1st through 3rd the power bands are cutting out at top peak. 4th and 5th it's hitting just right. On take off it's sluggish. Powerbands take too long to kick in. I'm not any good what so ever at carburetor adjustment. Where it's at now is the best I can get it.
First things first: How recently have you cleaned your carb?
@@Fixyourdirtbike recently. Engine has about 2 weeks worth of riding since rebuild.
@@Fixyourdirtbike I messed with it and got it pretty close. But I noticed the power valves are not working on low RPMs. Powerbands are on the pipe only. I'm trying figure how to adjust the power valves to come in a little early.
@@Fixyourdirtbike I got a question, can the power valves arm come loose? I took the cover off the left side because I didn't want to take the pipe off unless I had to. And I cranked it up and the valve didn't move reviving it up. Or can I determine anything that way?
Do you know anything about racing carburettors I have a racing carburettor on one is it any different
first it fouled while ideling then I put a new plug in and it lasted one tank.then the next day I started it idled fine then I rode like 100 yards and it fouled out while riding.i took it out and its wet and dark and will not spark anymore.
I would start by changing your main jet to a smaller size.
Hello I've been watching your video trying to tune a 96 ds80 just put this in the rings in bike is running and runs good but dies after 10 15 minutes have gone through the car and adjusted the flow also clean the car but it was very clean do you have any ideas that I may try?
I have Yamaha 125Z catalyzer... I just changed carb to UMA 30 but it make unstable sound from exhaust... Should i modify block and piston little bit big...? Or make some change in hole of air on block..?
You shouldn't need to modify anything past the reed valves. It just sounds like your air/fuel mixture isn't tuned right. What carb did you have on it before the UMA 30?
Fix Your Dirt Bike Mikuni 28... I change it wondering to make some speed performance...
Ok. 2mm Isn't going to make a huge difference, but if you want to get more power you will need to upgrade everything in the air/fuel and exhaust system. You would need to get a performance exhaust system to match your new carb to see a difference.
Fix Your Dirt Bike yepp... Thanks sir for your guide... Will ask again after fix it... 👍🏻😅
Wassup my KTM 250 2 stroke is acting up so when I ride it and try going on 4 gear it slowly turns of by itself and sometimes when i barley turn it on and put it on first gear then on second gear the throttle goes on it’s own with out me even giving it gas what do you think is wrong if you can help me out I would truly appreciate it
Bogging and taking off, that's interesting. When was the last time you cleaned your carb? Have you changed elevation or has the temperature changed significantly before you started having issues? When was the last time you checked your reeds?
Can you do a video for how to fix the choke on Honda CR 250cc.
what's up man just built a water-cooled motor.motor runs and idle but when I throttle it bogs but if I run choke up it response like how it should be if it's down. running a 33 Keihin carb main-142 pilot-52 needle clip one up from the middle. but question is way does it bog? I'm assuming it's my pilot to small??? I'm like 2 & 1/2 turn out on pilot screw from the body.lmk thanks
Is you engine cold or warmed up when that happens?
Hey man I have a 2000 cr125 and I rode it a week ago and it ran like a champ. I kick start it today a week from last time i rode it and it kicks over first kick but wont idle. If i let off the throttle it immediately dies. Any tips?
It sounds like your idle circuits are gummed up or your plug is fouled enough to still run but not idle. Check the plug first, and if that's clean you'll need to clean your carb.
@@Fixyourdirtbike Thank you so much man. Appreciate getting back with me! Gonna grab a new plug this weekend and throw that in and see if thats it first. I'll let you know how it goes!
Hi! My bike starts, goes ok on idle (maybe a lil too high) but when i give throttle the gas hangs for a bit and slowly goes down, I dont think i have it too lean. Anything i can do to fix??