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For sure will man! When I’m done restoring it I’ll show you guys the finished product!
Hey guys, back with another question for you. I can get my yz125 started now, but only if I pour fuel in the cylinder and when it starts, it idles extremely high (sound like it’s about to blow up lol) I have adjusted the air screw and the idle screw every which way with the same result...
I have also disassembled the carb and cleaned it like three times. It’s spotless in there. However, when I check the plug, It’s dry. Any suggestions? This thing is so close to being done, and I will not accept defeat!
thanks again,
Josh
Carb slide may be hanging up, cable could be too short or pulled apart at the adjusters but it sounds like a major air leak/ lean condition on why its running so fast. To check the carb slide pull off the subframe/airbox look in the rear of the carb and make sure its seating all the way to the bottom and do this turning the bars full lock left and right and watch to see if the slide is moving when the bars are turned, if its moving you have cable and or routing issues but you should be able to see that the slide is bottomed out. If you don't know how far down is bottomed out the disconnect the throttle cable and then let the slide go all the way down to get a reference. If that's not it then its time to check for airleaks.
Also make sure your stator plate is mounted where it needs to be because if your timing is advanced too far it can cause both a run away idle and very hard starting so check your timing.
Does the throttle have free play? If no, is the throttle cable routed correctly? From memory it should go below the tank bolt.
Does the rpm stay high when turning the bars to each side or does it go up or down? Could be the cable is too short. In the UK there is a brand that makes cables a tad too short (at least they used to for a YZ 250). Always used genuine after that.
Is there a split in the boot between the carb and reeds? Possibly caused by a short cable yanking the carb up when turning left.
Does it idle high with the choke off?
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Yea I already adjusted the slide and it is as far down as it will go (about a half inch from the bottom) However, I pulled the reeds and I could see just a tiny crack of light. So I fixed that and now the bike starts first kick every time. The idle is still sky high tho. I inspected the intake boot and can’t find even a hint of a crack...
Yea the throttle cable is routed correctly and the idle stay high with choke on or off and no matter how I adjust the idle screw or air screw. I will however see if the idle stays high when I turn the bars. I had a Ktm that did that once...
So were
obviously getting too much air because when I partially cover the back of the carb (when the air box and subframe are off) with a piece of cardboard, the idle becomes more normal
Tank sitting on throttle, pulling it dick strand tight?
Half an inch? Sounds high to me.
Cdi box.
Spray contact cleaner around different connection areas between carb and cylinder, spray areas where the cases meet. If the idle changes you’ll know where the problem is.
Take a picture of the back of the carb and show us how high the slide sits at “idle”.
My phone won’t allow me to upload a photo or a video on this platform for some reason...
You had this all the way apart, it needs a crankcase pressure test as it sounds like you have a leaking crank seal, gasket, or center case sealing.
Quite possible. But that above mention of a half inch under the slide seems to be a red flag.
so how would I go about running a crankcase pressure test? and how can I know if the slider is too high if I cant adjust it anymore...should I just get a new cable? I ran a compression test on it and got 125 psi...does that relate to the crank case pressure test at all?
Here is the link to what my bike is doing:
https://youtube.com/shorts/8wdCYV00GYg?feature=share
Disconnect the throttle cable and see how far the slide goes down without the cable attached to the slide. 1/2 inch sounds way too high.
Pit Row
How did you fix the “crack” in the reeds? Reeds cannot be fixed, they should be replaced. I know on some older model carbs you could put the slide in backwards, that not the case eh? How far can you twist the throttle? If not much until it stops, that means your slide is not going all the way down. As someone else has mentioned I have seen where mounting the tank smashed/tightened the throttle cable. Getting too much air it sounds though if it’s not a throttle cable/slide issue.
video is private.
Yea you’re right, I did that and the idle came down to a much lower level-almost a little too low. I’m playing around with it now but think I need a longer cable
Ok guys the idle is now perfect! I think the guy who owned the bike before me put the wrong cable on it because it’s about an inch too short so ima just order a new cable. Thank you all! Hopefully that’s the last of my troubles on this thing lol
Are you sure it’s too short? There is an adjustment on the throttle and often times on the top cap of the carb saw well.
Make sure it's a genuine one as mentioned previously.
Make sure the cable is adjusted properly before ordering a new one
Yea there are 2 places to adjust it which I already did to the max
You want to adjust the cable adjusters to the minimum or shortest for the cable housing which makes the inner cable itself the longest. Maximum adjustment on the outer cable makes the inner cable "shorter" and can cause the slide to not go all the way to the bottom of the carb body.
Just want to give some credit to the woodruff key ideal. I had mine in, but somehow the rotor slipped when installing and the timing was off. Once I took it off you could see where the key was "pressed" into the side of the rotor rather than the slot. BINGO! Starts first kick now!
Make sure the slide is all the way down and knocking bottom and you have free play in the cable
Great to see ppl helping someone out, this is what forums are supposed to do
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