YZF 450 Top End Rebuild

I just recently rebuilt the top end on my '03 YZF 450. I started up for the first time and let it warm up for 3-5 minutes. I then took it for a ride in first gear and after like 2 minutes in died. I then started it up and let it idle sitting still and it idles fine. I then rode it around for 3-4 minutes in first and second gear and it died again. It's like it's locking up or something. It idles fine on the stand, but when I'm riding it around it keeps shutting off. Any ideas???? Any help would be appreciated.



Starving for fuel?? How long has the carb been sitting? When was the last time it was cleaned? I'd start there...

Sticking float hinge, blocked gas tank vent or in-line vent valve, maybe. The in-line valve could be inverted. Just because you haven't had the hose off the cap doesn't mean it's right. I know someone who occasionally turns them over for fun. :thumbsup:

I installed one of those anodized MX plus gas tank vent caps over the winter. The one with the tubing that connects to the gas cap and then the aluminum cap on the top that lets air through. Could this be the problem?? I can get air through, but not much.

Air only has to enter as fast as the fuel leaves.

Air only has to enter as fast as the fuel leaves.

What a wierd concept.

If we were in Arkansas drinking a 12 pack, I'd suggest he ride around with the cap off and see if that help er out.

Being that we aren't....maybe he ought to ride around with it loose with the stock cap on.

Why do people buy metal gas caps, BTW?

Not a metal gas cap. It's an aluminum one way vent on top of the tube, which is attached to the stock gas cap.

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