2009 YZ450 won't stay running after it warms up

I'll try that. If that's the problem though, why would it start right back up? Wouldn't it not start until it cools off?

 

I learned a long time ago that an intermittent electrical fault can do almost anything it wants to, and probably will.  I stopped trying to make sense of every single condition.  The hardest part about them is trying to catch them when and while they are actively at fault.  Otherwise, you're down to guessing and troubleshooting by substitution, which gets awfully expensive, since electrical components are not returnable, as a rule. 

Try a new spark plug my bike did the same thing and it was a bad plug

I was thinking about buying it. That bike has a brand new head And valve train. If I'm not mistaken a new top and bottom too. Are you in MS? I'm in Oxford. If you get it right we should ride!

I'm in Jonesboro, AR. I plan on riding over at Covington soon.

Try a new spark plug my bike did the same thing and it was a bad plug

I put a new plug in it. Its black already. Edited by pastranafan5

I put a new plug in it. Its black already.

If it's black already your probably running a little rich if I'm not mistaken you should probably just tear apart the carb and give it a very good cleaning from top to bottom and change your jets also see if your accelerator pump is in good shape

A black sooty plug can be caused by faulty ignition, even with perfect jetting.  Also remember that unless the plug is allowed to reach operating temperature and stay there for at least 5 minutes, it will not turn dry and tan looking. 

Use an inline spark tester to see if you are losing spark when it kills.

Jrice2012 where in Mississippi. I just bought an 09 in Mississippi I'm rebuilding.

Jrice2012 where in Mississippi. I just bought an 09 in Mississippi I'm rebuilding.

the Op owns the bike I am referring to. It was bought in Southaven. I live in Oxford, but mainly ride at a few tracks in tupelo and Pontotoc. Sometimes go down to Jackson for the jetwerx compound. Where you from?

Columbus. I ride at 886, vet, Booneville. About everywhere. We've probably crossed paths. Im a slow vet rider on an old yz450.

Columbus. I ride at 886, vet, Booneville. About everywhere. We've probably crossed paths. Im a slow vet rider on an old yz450.

I'm riding vet Saturday. Did you race Booneville back in September? We Probably have crossed paths. I'm on an 08 yz450

We hit a couple races up there. One got rained out after first moto. We racing at Longhorn Arena Sat up in Muscle Shoals

We hit a couple races up there. One got rained out after first moto. We racing at Longhorn Arena Sat up in Muscle Shoals

Muscle shoals is a good ways from me. Did you race the Starkville arenacross this past Saturday by any chance?

A couple from our bunch was there. Both my bikes are down currently

A couple from our bunch was there. Both my bikes are down currently

The guy that bought my old rmz was there. He was from Columbus. I think he said he had a track at his place. I think his name is Jason? There was a girl rider with him too. I THINK her name was mckayla. She had a yz250f, and then some guy on a 125. Would that happen to be your bunch? Haha

Yep!! U met me. I was the big guy

Yep!! U met me. I was the big guy

Oh okay! Small world!

Here's an update on my bike problem. It finally got warm enough to check it out. I checked my ohms and found out the spark plug cap was bad. $20 later for a used spark plug cap and the bike runs fine. Thanks so much for the help. I never would have guessed an electrical problem.

Mine did the same thing until the rod came out of the case run good gets some heat stall out fast cool off and run good and then new motor

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