08 450 restart Issue

1 reply to this topic
  • mark twiggs

Posted January 21, 2013 - 09:23 AM


I hope someone can point me in the right direction on how to solve this problem. Here are the details

Northern California 60 degrees
Altitude up to 1500'
168 main
48 pilot
stk leak
2 turns out air screw
FMF 95dba spark arrestor
06 cdi
60 hours on motor

The bike starts fine cold. When it is warm or hot if I crack the throttle 1/4 open it fires the first time, if it does not start on the first kick it could take me 10 kicks to get it going hot start does not matter. It will sometimes start if I hold the throttle wide open after a half dozen kicks. If it sets for 30 seconds or crack the throttle 1/4 it will start. I had it hicup(stall) 4 times in a race yesterday and took me forever to start it. In the pits 3 guys had to push me to get it going. It runs great.Nice to loose first place because it won't restart. I get no decel popping. I'm going to check the valves today. ANY IDEAS? I had a 45 pilot last week which made no difference.

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  • grayracer513

Posted January 21, 2013 - 10:38 AM


The pilot looks rich, and the bike is acting as if it is, too. If it NEVER pops on decel, that's one indication it's too rich. When they're correctly jetted, they do that. Not excessive popping, just some.

Another clue is if the bike has a tendency to stall when the throttle is suddenly closed after being opened a quarter or more under load at low RPM. That happens because the rich pilot makes it "idle down" (transition from the main circuit to the pilot circuit) too quickly, letting the engine drop too far below idle speed.

Try a 43 or 45 pilot and re-trim it.

Never hurts to check the valves, too, but that's not what's causing this problem.

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