Most snowmobiles are 2 strokes. Wherever you got that info must be the same people telling everyone that Bush is raising the gas prices!!! Just bustin on ya. Definetely check frame in front where shocks mount. Check whole front actually, this is just most likely place. I bought one with a chassis that's in AWESOME shape compared to any I've seen from that era (Mine's an 89) The only bad bearings were the pivot bearings on the swingarm, and I replaced them. Unfortunately, the motor was another story but I bought a new cylinder, and just put it on. Didn't have a chance to tune yet and I bought a 06 z400!! The lt is sitting in back yard with a fouled plug (I didn't have time to tune it and I really wanted to ride with my brothers and buddies and for your motors safety better rich than lean) I did drop the jet size but still too rich. I think I may have a partially plugged silencer or the linkage in lower end of motor for powervalve set up wrong. That's why I say I didn't have time.