07 YZ450 Idle when hot

No replies to this topic
  • 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?


Related Content


yz250x vs 450 4t comparisons (preferably desert riding) needed by JakeNorthrupYZ450F

Dirt Bike   Make / Model Specific   Yamaha   Yamaha 2-Stroke
  • 9 replies

Is it worth it? (Cam and High compression piston) by macgi77

Dirt Bike   Make / Model Specific   Honda   CRF 150/230 F/L
  • Hot  36 replies

Thinking about Yamaha 250... by Arctic Pride

Dirt Bike   Special Interest Forums   Pro Racing
  • Hot  491 replies

yz400f throttle bog by yz400fmaniac

Dirt Bike   Make / Model Specific   Yamaha   YZ 400/426/450
  • * * * * *
  • Hot  28 replies

First Hare scramble tips by dhend8

Dirt Bike   General Dirt Bike Forums   General Dirt Bike Discussion
  • Hot  33 replies

Join Our Community!

Even if you don't want to post, registered members get access to tools that make finding & following the good stuff easier.

If you enjoyed reading about "" here in the ThumperTalk archive, you'll LOVE our community. Come join ThumperTalk today!

The views and opinions expressed on this page are strictly those of the author, and have not been reviewed or approved by ThumperTalk.