After about one week my new Vance and Hines SS2-R slip on is sounding really good. The only thing is, it has popping when the bike is decelerating around 6500 rpms. There is no flat spots anywhere in teh throttle and runs really good with no overheating issues. It justhas a real noticable poping noise around 6500 to 5000 rpms when the bike decelerating especially going down hills. Theprevious owner of the bike told me it was jetted and yestersday I discovered a K&N filter. Other then that it runs super. Is the popping more of a lean or rich condition when the bike slows down?

 

Lean conditions cause backfire/afterfire, my guess is that your jetting isn't set up right.

My bike does this too, I haven't been bothered to get it jetted yet.

 

UPDATE: Today I ran it until it was up to operating temp.Inside my garageI revved it up to around 7000 rpms for about 20 seconds then immediantly shut it off. After the engine was cool enough to touch, I pulled the two outer plugs to check the a/f ratio. Both plugs showed that the motor was running a little rich because the top electrodes were dark gray with a tad hint of black. As the electrodes tapered down, there were shades of brown on the sides as well. Can the bike run rich while under throttle but lean once the throttle has ben let off?

 

just to clarify things, what part of the plug do you "read" in order to tell the a/f ratio?

 

The ceramic around the electrode, just a guess but without the rush of fresh air into the airbox which is pressurized could cause you to run slightly rich... You're tossing it a bunch offuel without much airflow.

I think the best way to test it is to go out for a quick ride how you regularly ride the bike, then check it right away.

 

are your sure your valves aren't sticking? how many miles on the bike? and when is the last time you had the heads given the ole once over? a stuck valve will free under stress( i.e. acceleration) and then go back to "sticking" under deceleration or at less tourqe'y situations...the new valve guides are like what $20 for these bad boys and well..might fix your problem if you dont mind the wrench time.....also is the pipe longer than stock? that could be your culprit

 

why would a longer pipe be the culprit? Also there is a tiny little leak where the pipe slides onto the header where I couldn't the clamp to seal it off. What a tiny little leak that far back cause the popping too cause where the can meets the pipe theres a leak too but but it's only held on by springs.

 

Running rich and air leak would cause the popping. Mine pops like mad when on the track braking hard after been at the red line in 3rd and 2nd gears. No big deal.

 

I've come to the conclusion that it is runnig lean but not really bad. It's still very driveable but it doesn't have snap it use to have from 8,000 to redline. The plugs do look lean but not at any bad critical point. Now I suppose I better find some bigger jets.

 

did you know since you are jetted depends on how rich or lean you are running with k&n with a header it will balance out i was running sick rich with a level 3-4 jet kit i put k&n filter 2 brothers slip on with a aftermarket header it runs friggin awsome with no burning eyes