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Carb problems

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I just bought an 03 CRF 450 and its really clean just need an intake valve adjustment. But the carb had gas in it for like two years and i cleaned it out. Its starts and idles fine but it backfires real bad when you are engine braking. Any ideas on what i should do?:applause: :applause:

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I will deffinetly check that again. Ive gone through it a couple times now maybe im just not going over it good enough.

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I just bought an 03 CRF 450 and its really clean just need an intake valve adjustment. But the carb had gas in it for like two years and i cleaned it out. Its starts and idles fine but it backfires real bad when you are engine braking. Any ideas on what i should do?:applause: :applause:

My 02 was doing popping alot during engine brakeing,, I came on TT and posted the question, basically I was told to back the air/fuel mixture screw out 1/4 turn and go from there, I did that and my popping was solved... that might help.. :lol:

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The reason that you get backfiring is because you have a mixture lean enough to ingite in the exhast. When the throttle plate closes you stop the flow of fuel from the needles/main jet and you create a lean condition. When you are at idle (throttle plate closed) you are using the pilot circuit of the carb. Turning the fuel screw out to allow more fuel should take care of the issue unless the pilot system is clogged. If you are using a ZipTy type screw or the Motion Pro adjuster this adjustment is easy.

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