07 YZ450 Idle when hot

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  • jlkfg

Posted March 19, 2012 - 06:47 PM


About 5 minutes into my last 2 harescrambles / GNCC it starts to stall at idle. I will literally still be coasting into a corner with the clutch in and the motor just stops, happened several times per lap, very frustrating. It generally has a too high hanging idle or drops down during the race, seems lean. Usually it is difficult to start, hot start or not. The most reliable starting method in this situation is to give it a bit of throttle. Off idle was a little erratic during the race. I'm looking for some input on what to check/do.

I heat it up and run it around the yard etc for 20 minutes, idles fine, starts right up with hot start. I know it's not as hot as during a race, though.

07 YZ450
165 Main
42 and 45 and 48 pilot have been tried and cleaned and tried again.
450 ft, 80 degrees
200 hours on bike, recent piston/rings/cylinder/timing chain. (mostly precautionary).
Intake valves were done at 100 hours and have not moved since initial break-in. I checked them Saturday and all are in spec.
Carb boots are tight, carb cleaner test is good.
TPS is plugged in

1 - I am planing on checking the electrical stuff, stator and coil when hot.
2 - Unplug TPS
3 - Replace hot start o-ring #41
4 - Replace slide seal #11

Anything else, or any of these not to do?


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