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yzf450jack

popping at 1/4 throttle

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My YZ450/470 is popping in neutral at 1/4 throttle tryed a bigger pilot jet 45 changes nothing 48 changes nothing I put an edelbrock carb on same popping it idles good starts on first kick but at 1/4 throttle it's popping and the pipe starts glowing :cry: so the carb is not the problem So Anybody know whats up.........

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Nope not exhaust leak not in carburetor i tryed a differant carb still popping like it's very lean.I can make it rich and still popping you think the exhaust valves going bad :cry:

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My YZ450/470 is popping in neutral at 1/4 throttle tryed a bigger pilot jet 45 changes nothing 48 changes nothing I put an edelbrock carb on same popping it idles good starts on first kick but at 1/4 throttle it's popping and the pipe starts glowing :cry: so the carb is not the problem So Anybody know whats up.........

The pilot jet doesn't affect 1/4 throttle opening - that's the needle. Go down one clip position...

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if both the stock carb and the edelbrock pop at the same place then it's not going to be the stock needle thats causing the popping.

Assuming you dont have leaks, check the fuel, the cdi, the tps, and the stator. It's all you have left. :cry:

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mine a long time ago, had the same problem, my solution with to file down the stopper of the carb clamp, so it sealed better, pop went away.

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Have you checked your inlet manifold for leaks. I split mine in two places on my 426, but as someone else mentioned, the clamp spacers can restrict the proper clamping force required to effectively seal the manifold to the head and/or carb'. Worth a look..... :cry:

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Yes checked intake for leak im good If you cruz at 1/8 throttle with no load on the motor it don't run smooth but runs hard everyware else :cry:

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