i bought a 00 426 a couple months ago and initially had the plug fouling problem... but i think i figured it out. but more recently ive heard a strange noise from the left side of the engine. sort of a "sssst sst" after i let off the throttle and when im revving it. it also smokes more than usual when i start it, though it stops once its warmed up... it also has started to backfire when revved. it ran great when i got and i havent touched the carb. im wondering if the cam chain is loose and screwing up the timing... any thoughts?