i just installed the fmf megamax on my 99'sportsman 500.i figured i'd have to rejet, but i just want to make sure im doing everything right. decided to run it with no discs, for more airflow. but when i get off of the gas it pops on deceleration. this is due to a lean engine correct?so is there an air/fuel screw i can tinker with to richin it up? im trying to avoid going out and buying a jet kit since moneys running low, but ultemently i think im going to have to. thanks alot

 

that sounds to me like its just back firing

 

If it BACKFIRES through the carb on accelleration, it is usually too lean.
If it AFTERFIRES through the exhaust on de-acceleration, it's usually too rich.

Usually if you install a less restrictive exhaust system, the air flow is increased, thereby requiring a richer mixture.

The air/fuel screw should only have an effect on the idle circuit (and slightly above).

If it's a mild poping, this may be acceptable. A check of the spark plug would give you a better idea of it's running condition.

 

yeah i think i'll check the plug tommorow, i dont think its backfireing, since it pops about 10 times coming off the throttle, but im not sure

 

Put the discs back in the muffler they are there for a reason .Takin the discs out can harm your engine and prolly give you less performance than with them in.