WR426 pop pop snap

2 replies to this topic

Posted March 28, 2015 - 07:03 AM


So since ive gotten my 426 running again Ive noticed its been popping and snapping even at idle. I always thought this was because the bike was jetted for a higher elevation and too lean for where im at (sea level). Since I had the carb apart earlier in the restoration process I went ahead and got a new sigma jetting kit off ebay. Now I believe its a bit rich since it only likes to start without the choke and will flood with the choke on. When running though it still pops and snaps at times. does this have anything to do with the muffler? Its an old fmf Q series unit but the label has been worn off so I cant tell what it is. Its also very loud, which leads me to believe it is the muffler, but thought I'd post and get some kind of confirmation.

Thanks guys

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  • Pooley

Posted March 28, 2015 - 04:00 PM


Any Q series FMF should be pretty quiet in comparison to a YZ or non-spark arrested, non-quiet designed pipe.  The pipe is designed to reduce sound to below 94dB.  If it is loud, repack the silencer.  I HAVE had a poorly packed, or worn out packing affect my jetting, or at least the sounds coming out of the end  of the exhaust.


Posted March 30, 2015 - 10:32 AM


I ended up going out riding on Saturday night.  The bike performed great, and the popping and snapping seemed to go away as the bike got warmer.  I got some repacking materials at cycle gear just in case and will repack it just to be sure.  Thanks for the response


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