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Pressure Test
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Posted by: rider1234

Did a compression check on the 50 and got 90-95lbs. Seems low so I was wondering if anyone has ever done a pressure check on this engine, if so how many lbs of air do i put in the engine?

Posted by: bulldogfallon

I would think that 120-135 would be a decent pressure check.

You don't put air into the engine to increase the pressure.....

You may need to rebuild the top end (piston, rings, etc) or at least the piston rings to regain some compression.

How many hours do you have on the quad?

Posted by: rider1234

I know you dont put air into the engine LOL. I want to do a leak test. PLug up exaust hole and put a pressure gauge on the intake side. fill engine with air and let it sit and see if air pressure is lost. Then you know you have a leak somewher. Im just not sure how much air to put in this small engine.
MAy be piston rings though. whats a good way to tell if the rings are worn.

Posted by: dblacks

remember, all compression testers are not created equal.

Make sure you have a good seal at the cylinder as well as at any connections on your tester

Posted by: drr5

do the rings at leas if not the cylinder, should be right around 130lbs just did the top end on our bike vast improvement over 90 lbs of compresion. by the way thanks gary for getting those parts out to cheater motorsports that quickly. pat

Posted by: camsdad

to answer your question 10 psi on the leak test ...

Posted by: rider1234

Thanks. Rings and Pistons only have about 10 races on them. Would a bad crank seal cause low compression?

Posted by: camsdad

no to crankseal......but remember like dblacks said it may be you compression tester....i have 3 high quality testers that all read different...i use the same one everytime so i have a baseline...