Other yz426 idle problem...

ok guys here the situ... i've been battling a problem with my idle since i've got this bike end of last season. it's cost me some top spots in races due to getting into tight sections and the idle dropping way too low and stalling then being hard to start as is the nature of the manual decomp beast(that's gonna be solved shortly with a 450 cam but that's another thread all together)

anyway i adjusted my idle finally and it seems to be set great, problem is now when i crack the throttle after the bike is warmed up on the stand with the choke off and everything the idle will hang for sometimes up to 30 seconds before it levels back out to a nice solid steady idle. i've cleaned my carb and jets, lubed and cleaned the throttle and return cable and everything.

also my fuel screw does absolutely nothing. i can screw it all the way in and no difference, all the way out and nothing... should i go up one on the pilot jet?
 
I'm no genuis by far, but it sounds like you have a vacum leak. I'd check all potential spots, like the hot start knob, carb boot, or even those seals on the slide of the carb. Where's Agent Smith when you need him?:noidea:
 
Check for leaks with some carb cleaner. Get an idle going that is somewhat steady. Spray around the carb and the carb boot. When you hit a leak the idle will change from the carb cleaner getting sucked in.

It sounds to me like your carb is just worn. It can develop wear on the slide where it doesn't seat at the same spot each time. I have this on my bike. The other thing to check is the cables. Makes sure they are not too tight. There needs to be a little play between the pull and push cables or this kind of thing can happen.
 
All the above! You could be dealing with a worn carb and all the cleaning and jetting tweaks is not going to fix it.

I made mention of the Needle Clip, because I slipped into 2 stroke daze and when that is a symptom of a 2 stroker, you adjust the clip.

If you have no leaks and this was doing it since day one, what are the mods and jetting specs? If you are stock and the jetting is not, you should go back to stock and work your way from there.
 
thanks for the input guys. i'll try the vacuum leak idea tomorrow morning and recheck my cables and see what happens. grayracer on tt mentioned a vacuum release plate or something that could be in the wrong way but for the life of me i can't figure out exactly what he's talking about.
 
thanks for the input guys. i'll try the vacuum leak idea tomorrow morning and recheck my cables and see what happens. grayracer on tt mentioned a vacuum release plate or something that could be in the wrong way but for the life of me i can't figure out exactly what he's talking about.
That's the little seal/plates, on the slide of your carb. They could be in wrong, or wore out.
 
roger that, my fuel screw's oring is new and in good shape. i just had it all apart and did have to replace it but still didn't help my condition. today i sprayed some carb cleaner around and no vacuum leaks so that's good. next step as you mention is a size up on the pilot. i'll keep ya'll posted :wink: thanks for the input :thumb:
 
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