Need help with fixing decel popping

Hey guys,


I've posted about this before on here and got some good suggestions but I'm still in need of some help.

Some background, I have a 2012 WR450F, with a full akrapovic exhaust system (spark arrestor/baffle removed), and the issue is that whenever i close the throttle the bike makes an annoying popping sound pretty much until in come to a stop or turn the throttle on again.


Now someone suggested to adjust the idle fuel cause it sounds like a lean condition, so I went and bought the $150 FI diagnostic tool (not the GYTR tuner) and adjusted the CO level. I tried everything even went to the maximum +30 CO level and it still popped on decel, and i even went the other way down to -15 and no change.


I've also checked all the exhaust connections and they're fine, pulled the entire thing apart and put it back together.


I'm at a loss as to what to do at this point, any suggestions would be great. I would have just put the stock exhaust back on by now but I don't have it cause the guy I bought the bike from didn't have it, go figure.

What Map are you running?


If you are in the minus setting raise them by 1 until 


I had same issue with the yz450 2014 i had if i went to low with the gytr tuner setting it would pop

Running one of the FMF maps, most of the fuel values on the map are +3 or +4.

Did you replace the header crush gasket when you put on the new exhaust?

Not sure if it was replaced, the exhaust was on there when i got the bike, ill buy a new one and see if it changes anything.


thanks for the suggestion.

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