Erratic Idle Speed

[Homewrecker]

I recently picked up an '04 YZ 250F.

After I start the bike and take the choke off the bike idles fine. However when I gun the throttle (in neutral) the engine does not return to its original idle speed and races at an elevated RPM. It does sometimes return to normal after a while but most of the time it doesn't.

I have tried to use the idle speed screw to bring the RPM's down but the engine almost stalls because the screw would then be set too low when the engine returns to the normal idle speed on its own.

I'm still reading through all of the tech articles on carburetion but I decided to post in the meantime. If the engine supposed to return to idle alomost immediatley after the throttle is revved/gunned?

Any input would be appreviated.

 

[chevy383cid]

Sounds like maybe your pilot circit is restrected,try cleaning the carb. and blowing compressed air through all the passages,wile your at it, throw a new pilot jet in,look up the part number and find out what stock size is and compair it to what is in the carb. now. maybe go 1-2 sizes larger.