Idle adjustment on YZ 125

OneDirtyMXRider
Edited Date/Time 1/25/2012 2:00pm
Im working on a 2001 yz125 and im am having trouble with the idle adjustment. Do i turn the idle screw to the right or left to make the idle higher? I can usually figure this out but am having a little more problems than usual.

What the problem it is having is when kicking the bike, it seems like it just doesn't have enough ump in it you start up, i figured the idle was low on it and if i adjusted it to a higher speed it would start.

My second though was one of the jets in the carburetor, I'm pretty sure theirs one jets specifically for start-ups but not sure which one, i might go ahead and clean it out just for the fun of it.

I have looked through the Clymer Repair manual book and it doesn't say which way to turn it, so that leads me to you guys.

Thanks for all the help.
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mx5471
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mx5471 11/30/2011 5:12pm
11/30/2011 5:12pm
On every bike you turn the idle screw in, (clockwise) to raise the idle rpm. The screw raises the slider as if you were twisting the throttle. Has nothing to do with mixture. More info is needed. Does the bike start? If not ,turning that screw isn't going to help. The bike has to run before you can set the idle. From what you said, (not enough ump), to me sounds like no compression. If you have never started the bike, the possibilities are endless, and from what you said, you don't know much about a motor on an mx bike. It's commendable to do things on your own, but I think you should take it to some one that knows what to do if you want to ride it. It's obvious you have never worked on a bike before. If it doesn't start, check for spark, compression, air flow ,and gas. Find a guy at a track close by that will help you for a few bucks. Clymer books don't help. Good luck.
OneDirtyMXRider 11/30/2011 5:21pm
11/30/2011 5:21pm
mx5471 wrote:
On every bike you turn the idle screw in, (clockwise) to raise the idle rpm. The screw raises the slider as if you were twisting the...
On every bike you turn the idle screw in, (clockwise) to raise the idle rpm. The screw raises the slider as if you were twisting the throttle. Has nothing to do with mixture. More info is needed. Does the bike start? If not ,turning that screw isn't going to help. The bike has to run before you can set the idle. From what you said, (not enough ump), to me sounds like no compression. If you have never started the bike, the possibilities are endless, and from what you said, you don't know much about a motor on an mx bike. It's commendable to do things on your own, but I think you should take it to some one that knows what to do if you want to ride it. It's obvious you have never worked on a bike before. If it doesn't start, check for spark, compression, air flow ,and gas. Find a guy at a track close by that will help you for a few bucks. Clymer books don't help. Good luck.
No, it does start, it just takes alot of kicks. It has a new Top end and good compression. I checked that. Its is really hard to explain but, it seems if the bike had more rpm when starting it would be easier. It Just seem like it doesnt want to start because the rpm is so slow. The Bike Does Start Tho, It has a Brand New Plug In it, Just Cleaned Air Filter and Fresh gas With 36:1 Mixture. I will admit, im not to good on working on my own bikes, but im trying to learn by myself so i can stop paying the local shop an assload of money. I have rode before, and raced. I have owned many bikes, so im not a retard.
mx5471
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mx5471 11/30/2011 5:50pm
11/30/2011 5:50pm
The only rpm the bike gets when starting it is how hard you kick it. If you can start the bike, and have it run, and let it warm up, and it idles, that's good. If you can ride it ok, that's better. When you kick the bike, it creates suction on the intake side to draw in air and gas, which makes it start. If spark and compression are good, I would look at the carb. Make sure it's clean, jets are clean,float level is good, and vent hoses are clear. There are not many parts in the carb, and you can get exploded diagrams of it on the web if you look for oem parts. It's not hard to do,just do it slow. But I'm still not sure what the exact problem is.
OneDirtyMXRider 11/30/2011 6:02pm
11/30/2011 6:02pm
mx5471 wrote:
The only rpm the bike gets when starting it is how hard you kick it. If you can start the bike, and have it run, and...
The only rpm the bike gets when starting it is how hard you kick it. If you can start the bike, and have it run, and let it warm up, and it idles, that's good. If you can ride it ok, that's better. When you kick the bike, it creates suction on the intake side to draw in air and gas, which makes it start. If spark and compression are good, I would look at the carb. Make sure it's clean, jets are clean,float level is good, and vent hoses are clear. There are not many parts in the carb, and you can get exploded diagrams of it on the web if you look for oem parts. It's not hard to do,just do it slow. But I'm still not sure what the exact problem is.
Okay Thanks For the Help, I will Probably take it apart tomorrow and Clean it out and see if the helps, It Runs Good once its started it just takes a couple more than usual to start. It Will Push Start No Problem But i don't like to do that. But, Thanks for the help, sorry if i wasn't to clear. I will update on what happens.

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mx5471
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mx5471 11/30/2011 6:24pm
11/30/2011 6:24pm
Push starting can give you a couple of clues.On a 4 stroke like Honda, the valves are shit and guys push start them all the time. On your bike,the stator may be the problem. Kicking it with a weak stator may not start it, but pushing it gives it time to generate enough juice to start, and once it starts it's fine. Only way you can fix that is to replace it. It's expensive, so try everything else first.
OneDirtyMXRider 11/30/2011 8:03pm
11/30/2011 8:03pm
mx5471 wrote:
Push starting can give you a couple of clues.On a 4 stroke like Honda, the valves are shit and guys push start them all the time...
Push starting can give you a couple of clues.On a 4 stroke like Honda, the valves are shit and guys push start them all the time. On your bike,the stator may be the problem. Kicking it with a weak stator may not start it, but pushing it gives it time to generate enough juice to start, and once it starts it's fine. Only way you can fix that is to replace it. It's expensive, so try everything else first.
Man, I was wondering if my starter was going out. I Was really hoping it wasn't something like that. I found a stator on ebay.

http://www.ebay.com/itm/1996-2004-YAMAHA-YZ125-STATOR-MAGNETO-GENERATOR…

I am thinking about buying this one if the carb cleanout doesnt help. I will also crank up the idle a little. May consider rebuiding the carb while its apart. How often do those usually last, I've had a magneto go out on a bike, but it was a crf 70.
OneDirtyMXRider 11/30/2011 8:07pm
11/30/2011 8:07pm
And with the stator, is that something i would be able to do by myself or would need a local shop to do?
mx5471
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mx5471 12/1/2011 7:28am
12/1/2011 7:28am
It's easy to change but I didn't say you need one. If I were you I would take it to the local shop and let them work on it a little bit to see if they can diagnose your problem.
mxtech1
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mxtech1 12/1/2011 11:37am
12/1/2011 11:37am
CLEAN THE PILOT JET
partialperson
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partialperson 12/2/2011 2:30pm
12/2/2011 2:30pm
Reeds will also give a symptom close to this, taking several kicks to start or an air screw that just doesn't seem to "adjust" to that just right setting with the motor sounding just a bit flat..
MOTODAD422
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MOTODAD422 12/4/2011 8:08am
12/4/2011 8:08am
I have seen many people trying to start their bike when cold and have a tough time, alot of times they are twisting the throttle with their kick,this almost defeats the chokes operation. With the throttle closed, the choke is so more effective because of increased vacuum needed to pull the fuel to where it needs to be. 2 or 3 kicks with the throttle closed and the choke on , and then about one quarter throttle and it should light. if not then check compression and your reeds.
OneDirtyMXRider 12/4/2011 1:04pm
12/4/2011 1:04pm
MOTODAD422 wrote:
I have seen many people trying to start their bike when cold and have a tough time, alot of times they are twisting the throttle with...
I have seen many people trying to start their bike when cold and have a tough time, alot of times they are twisting the throttle with their kick,this almost defeats the chokes operation. With the throttle closed, the choke is so more effective because of increased vacuum needed to pull the fuel to where it needs to be. 2 or 3 kicks with the throttle closed and the choke on , and then about one quarter throttle and it should light. if not then check compression and your reeds.
My Compression should be good, i have recently Re-did My Top End, i ill still check it tho. I was wondering about the reeds, when i did the top end they looked okay, but i will check those if its not something in the with the carb. I usually start the bike throttle closed, it used to fire up 1 or 2 second kick, cold start. I appreciate all the helps you guys have done. I will update what the problem was.

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