2011 backfire/popping on deceleration

4 replies to this topic
  • billygildark5007

Posted May 18, 2014 - 05:06 PM


Ok so I can't figure this one out. I did read the forums but they didn't help me. About 20-30% of the time my bike will pop on deceleration under compression braking. Adding +1 to my map seemed to help but doesn't fix. I did all I can think of. Valves are in specs. New exhaust gasket, cleaned all throttle body, injector(best I could, carb cleaner and air compressor) took apart fuel pump and cleaned filter, new plug, switched gas I'm using. This helped for 1 days moto. Today it started doing it again. Is it possible I have carbon build-up in the head causing a valve to hang open or worn valve springs? Or am I looking at a new fuel pump or injector? The bike doesn't seem to be starving for fuel, no noticeable loss in power. Need master grays help please. Or anyone knowledgeable

  • billygildark5007

Posted June 15, 2014 - 05:43 PM


If anyone still cares 2 motos tested it was the injector.

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  • kcrpkx125

Posted March 03, 2015 - 10:35 AM


Thanks for the answer I've been having the same problem with my 2010.

  • billygildark5007

Posted March 04, 2015 - 10:57 PM


Thanks for the answer I've been having the same problem with my 2010.

Not sure if it was the real answer now. A few rides later it was back. Backfiring like a shotgun under hard braking every time and hesitating (like a clogged pilot jet) and sputtering if your held around 5-6000rpm. Otherwise it was fine as long as it was over that rpm.

My ultimate fix was to get the dealer efi diagnostic tool (not the gytr tuner) and increasing the co level +6.

I don't know why that worked or what the real cause of the issue was.

  • grayracer513

Posted March 05, 2015 - 07:24 AM


The carbon monoxide (CO) level at idle is reflective of the mixture.  Richer mixtures produce more CO.  The dealer FI tool set the idle mixture richer, and it had the same effect as a larger pilot jet would have in a carb. 


The more I learn about the system the more I realize how simplistic it is in some ways.  Most automotive EFI's are programmed to cut off all fuel delivery at closed throttle under decel conditions when the engine is turning faster than about 3x idle speed.  If the programmers would have put that into the unit, say cut it off above 3000 RPM @ zero throttle, it wouldn't be able to backfire regardless of the mixture.

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