Hi, I'm a new guy here. I have a 05 S40 as my first bike for about a month. The backfiring problem is not as serious as I thought. I can eliminate it if I play the throttle carefully. But, when sometimes I engine brake at a higher speed and it backfires loud, the engine sound and vibration seem rougher after the backfiring. Is this normal? Do I need to play with the jet to make it work better?