Time for a rebuild or not?
#1
#2
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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
#3
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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
#6
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ranvette
Polaris Ask an Expert! In fond memory of Old Polaris Tech.
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07-04-2015 06:13 PM
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