xr650l popping on decel-help

4 replies to this topic
  • A-10 Crewdog

Posted October 03, 2007 - 04:49 PM


I am looking for a little advise from you "L' experts out there. I have an 06 with an FMF headpipe, Q muffler, snorkle removed, UNI filter and a Mikuni 42mm pumper from XR's Only. The bike runs great with plenty of power and throttle response with no flat spots. On decel from rated speed or between shifts I get a slight pop from the pipe. I thought it might be lean on the bottom so I went to a larger pilot but all that did was change my air screw adjustment, and the popping was still there. The air screw is at 1.5 turns out and idles great. The idle gets erratic at 2.5 turns out and .5 turns out so I think I am correct with the pilot. The Mikuni tuning guide tells me that some free flowing exhausts can cause this without being lean. I really did not think the "Q" would flow that much more to cause this. Any help would be great. Thanks!

A-10 Crewdog

  • Bibleman

Posted October 03, 2007 - 05:26 PM


Make sure you do the rest of the carb mods for one thing. Also, make sure the vacum line to the enricher is hooked up properly. It's the thing on the throttle side of the carb that has two screws holding a small plate on it. I have a similar set-up and my popping is almost completely gone but not totally. Don't forget to get rid of the smog stuff too - that's the most important step in reducing or eliminating the popping.

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  • martinfan30

Posted October 03, 2007 - 07:45 PM


sounds like you have the carb tuned pretty well. if its just a slight pop with no driveability issues, dont worry. as long as your temp is not getting too high. do the smog removal too.

  • Denn10

Posted October 03, 2007 - 08:58 PM


you still have the smog stuff on it?

  • A-10 Crewdog

Posted October 04, 2007 - 02:36 PM


The smog stuff is gone. Thanks.

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