I have a 99 KDX 200 made into a 220 with wiseco piston kit,also a full pro circuit exhaust with a add on spark arrestor, boysen reeds and hot rods rod kit.There seams to be alot of black smoke coming from the exhaust.Is this normal? I also ride at 8,000 ft in altitude. I did purchage the bike that was being driving at 4,000 ft. Is this something I can fix with re-jetting the carb or with fuel mixture?