i have a tc racing pipe on it. You know the one thats really loud. Because of the tiny silencer. anyways i think since on this pipe they dont use packng in the silencer is causing it. I really want 2 fix this. Also can the backfiring mess up the engine at all or cause any damage to the bike? just thought i asked

 

Is the carb totally stock? Air cut off valve still hooked up?
Im assuming you mean it pops on sudden throttle let off. And if its just popping, and not doing alot of loud backfireing, its probably not all that harmful. But its a sign of a lean pilot circuit.

 

ya the carbs stock. its jetted tho. The guy i bought the bike from said it had 2 do something with the d cells. Im clueless wut that is.

 

If the air cut off valva is still working and hooked up, then the idle mixture is too lean. Try giving the mixture screw a 1/4 turn richer, and that should enrichen the idle mixture enough to stop the popping on decelleration. Some pipes pop and crackle , and because they are so free flowing, theres not alot that can be done about it.

 

I dont think its your pipe, its probably in need of a rejet. Try going up or down one size on the main jet.
What jet sizes do you have in it and what mods are done to it besides the pipe ? - main jet - pilot jet.
Just for a baseline for starters, if the pipe is all you have done to it, try a 165 or 168 main jet. Depending on your elevation and outside temp etc. etc. that should get you close to start fine tuning up or down a hair.
Backfiring probably is not going to mess up your engine, but if its a lean condition causing the backfire then that will eventually tear up the engine.