7 replies to this topic
  • luvmythumper

Posted April 06, 2001 - 09:30 PM


Is backfiring typically the result of too lean or too rich. It is occuring on decceleration.

  • YZ400Court

Posted April 06, 2001 - 09:53 PM


Lean pilot or mixture screw will cause popping during decelerration, but that does not mean too lean. My 400 popps, but still has great pull down low and in the middle, I'm not changing a thing.

Pretend it's flat and give it the gas.

  • teamtoxic

Posted April 06, 2001 - 10:18 AM


Same here for my 426. Runs real strong but pops on deceleration. No big deal!


  • yzernie

Posted April 06, 2001 - 05:03 PM


Popping or backfiring upon deceleration is from a lean condition. In theory they should not backfire or pop upon deceleration. A little bit is probably ok but, you might back out your fuel screw 1/4 turn at a time to see if it changes the pop.

When I took delivery of my 01 the fuel screw was at 1/4 turn out from the factory. I have played around with my jetting and fuel screw and eliminated any backfire or pop when decelerating, even from high rpm. The bike pulls hard from the very bottom to the rev limiter.

Food for thought, yzernie

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  • yzernie

Posted April 12, 2001 - 04:28 AM


Did you get it to stop??


  • JBM

Posted April 12, 2001 - 05:16 AM


I have found that my bike runs best when a slight amount of popping occurs on deceleration.

  • luvmythumper

Posted April 12, 2001 - 06:51 AM


Still not resolved. part of a larger problem. Read my post under "still need help". Thanks for all the input.

  • Boit

Posted April 12, 2001 - 09:58 PM


I agree with JBM. I can adjust the "pop" with the fuel screw. If I adjust the screw such that I get no "popping", then the bike gets a little sluggish when I whack the throttle hard off idle. With an adjustment that gives the occasional muffled pop, I get the best throttle response. It should sound like a gurgle with a gentle snap...or pop when the RPM's get down around 3,000...or so.

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