I just got a 1999 skidoo mxz 670 H.O. it has 5500mi and has never been rebuilt i was wondering how long these motors normaly go before they need a top end rebuild and what the presure should be on a compression test. I did a test and i got 120 lbs is this good... bad..?

compression sounds alittle low . mybuddy's 98 mxz 670 has 13,000 miles on it and he has never had the motor apart. this sled still runs with 800 all day and he isnt nice to iti still have a 97 670 i bought used and it has 4500 miles on it and still runs perfect :banana: :banana: :banana:

120 is too low, should be more like 145. My '99 670HO has 4700 miles on it and the compression is still 145 to 150. Sounds like you need new rings. Just picked up an '04 600HO REV, it tested out at 120 psi, BRP is going to replace the rings as a manufacturers defect. So based upon that I'd say you need a top end.