03 yz450 Wont idle low

my 03 yz450 is backfiring under decel... and whenever i get the idle semi dialed, when i give it gas it kicks to a high idle and wont idle low again. any ideas

That is a "hanging" idle. Caused by a lean condition. Backfiring under decel is also either a leaky exhaust or a lean idle. Try dialing in the pilot screw first:

http://www.thumperfaq.com/jetting.htm#PJ

If that doesn't work, check for external vacuum leaks around the intake manifold, and check your valve clearance.

valve clearance will cause idle problem at low idle?

valve clearance will cause idle problem at low idle?

Yes..

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now