bike wont idle

just had carb cleaned at dealer, idled fine before that but started hard. now starts fine [with a twist of the throttle first]but will not idle. have continuisly adjusted the idle screw to no avail. will idle with choke on ,but very high. turn off choke bike stutters and dies. adjust idle screw... nothing happens ...nothing happens... then extreme hi idle with no in between. do i need a new idle screw? could it be catching or stretched? 2003 yz 450. first dirt bike.


If it idles with the choke on, but not off, logic points to it being too lean. If you just paid to have the carb gone over, take it back and make them do it right. It's supposed to run correctly when they get done with it unless you signed something that says it needs work that you decided not to have done.

yeah, just paid a guy to clean it, no tuning. it backfires alot off throttle too so it must be lean. all stock tho so dont no y that would be. thanks for help

should i start with idle mix screw first?

The thing is that when they clean a carb, unless they don't do anything more than hose off the outside, they have to remove the idle screw. If they remove the idle screw, they throw it out of adjustment. So before they give it back to you, they need to make it idle or tell you why it won't.

Was this a shop, or just some guy you know?

Check the clearances on your valves, then check the hot start to be sure it's free and closing completely. Then, be sure there's an O-ring on the pilot screw. Top to bottom, there should be an O-ring, washer, spring, and then the screw.

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