motor runs great at high r.p.m's,low idle not running so well . compression check, # 2 cylinder down around 90 psi from the normal 385. Is this motor toast or just stuck valves??

any suggestions ??

 

Sounds like a leaking valve seat(s). Does it smoke at all?

 

Put a teaspoon of oil in the cylinder and run the test again. You'll be able to tell if compression goes up if its valves or if its rings.

 

Do the compression test again. But do a bleed down test when you do the compression test.

What this is when you crank the engine over and build pressure on the gauge. After the gauge tops out. Stop cranking the engine and watch the gauge. If it holds at what ever psi your getting then most likely you have a bad cylinder. If the psi goes down after you stop cranking then you have a bad valve or rings.

 

Any updates?