Fresh Gas, Clean Air Filter, New Plug(gapped). Almost Seems like timing is off and pressure is coming back from the intake valve. Sputter is definately in the carb or intake valve vicinity. I was thinking dirty carb. I sprayed a bunch of carb cleaner in the carb while revving it very high. Bike runs pretty well sputter is only occurring 10% of my riding time. Bike does have pro circuit exhaust.

 

Make sure the air mixture screw is adjusted properly, sputtering can sometimes mean you're getting too much air. If this doesn't work, need to pull the bowl off the carb and remove the 2 jets, clean them out, and clean the bowl.