The other day we did a compression test on my 1997 sportsman 500. we removed the plug screwed in the tester and i turned it over with the electric starter. i could only get 70psi out of it. what should it be? tiem for a rebuild?

 

Average compression on a 500 engine with a gauge and throttle wide open is between 55-90 psi because of the cam detent assembly according to the manual.This allows the exhaust valves to open a bit while cranking to allow easier starts. It's not like taking a normal compression reading on most engines that would read much higher. If you're showing 70 psi doesn't sound bad at all. You can get it to build up more by cranking on the wide open throttle for a longer period of time,but don't expect much more than 100 psi. That's about as much as I've ever gotten out of one,even a fairly new one. OPT

 

With the 500s automatic decompression system it not going to show you its true operating compression. How many Hours/Miles?

Our 97 with 7000 miles still runs like it has since new.

 

it has 7000 miles too, i didn't hold the throttle open when did it, but if we put a new cam in and do the valves should i rebuild it anyway?

 

Have seen em with more miles than this on the same piston. Just do one thing at a time. "IF" the cam is bad replace it and the exhaust rocker arm as it usually gets scored up from the cam lobe. Then see how it runs. Simple to replace without having to tear the engine down. Look here under "intake and exhaust". Browse OPT

 

I had over 13,000 miles on my 08 500 and the beast ran like a top . Never used oil between changes if I would of kept it I'm sure it would of lasted well past 20,000 . Your just getting that thing broke in