03 CRF450 Issues

[coppertube]

Hello everyone, this is my first post and I'm hoping that someone can help me out a little. I've got an '03 CRF 450 that's giving me some trouble. First, it doesn't idle unless the choke is on (out). I let it warm up plenty when it's first started, but the second I turn the choke off it dies. It will run without the choke if I crack the throttle slightly. Should I adjust the idle? Next, when I rev the engine and let off it backfires as the engine decelerates. I generally get two or three really good pops. I feel like my fuel mixture is about right, although I have a suspicion that I could need to adjust my air screw. I'm about 1 turn out. Also, my intake valve clearance is with .001" of spec, but my exhaust valve clearance is about .014" and spec is .011". Would this cause the backfiring? Thanks very much, and I look forward to meeting all of you!

[Woody_393]

If valves are within spec as you say, I'd think you may have a header leak.

You've got me on the not idling though, maybe a plugged jet?

[dhighlan]

Go up on your pilot jet, this will help your idle and the decel pop. One turn out on the airscrew is right on the edge. I assume you made sure your decomp was set right when you check the valves. Also make sure you don't have any air leaks. If the pilot change doesn't seem to help at all you have a leak. As always make sure your float is correct or you will be spinning your wheels with the jetting.

[dhighlan]

I do have one question as to what you mean by your fuel mixture?