yz450f popping on decel. does this harm the engine?

3 replies to this topic
  • EricC1

Posted May 26, 2016 - 01:35 PM


Hi, I have a yz450f and when ever I let off the throttle/ engine brake the bikes pops a lottttt. Just wondering if this harms my engine in anyway or should I not worry about it? Thanks :)

Edited by EricC1, May 26, 2016 - 01:35 PM.

  • Wild Alaskan

Posted May 26, 2016 - 02:21 PM


probably not, but you likely have a header leak or a very lean idle mixture. It is hard on the exhaust packing

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  • grayracer513

Posted May 26, 2016 - 03:01 PM


"Some" is normal, and is actually a sign that the bike is jetted correctly in the lower third of throttle.  "A lot" is abnormal, and although it can be a little tough on the muffler, it's otherwise harmless.  Start by being certain you don't have an air leak into the exhaust at either end of the header.  If your exhaust leaks, you can run richer until it drowns the engine and never get anywhere with solving the backfire.  One you've done that, proceed with checking for a lean pilot circuit.







  • EricC1

Posted May 26, 2016 - 05:37 PM


Thank you!!

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