Taillight Posted August 22, 2016 Share Posted August 22, 2016 I have a 4 stroke atv question. when someone tells you that the atv is burning oil, is there a quick way to see if it needs piston rings or a valve job? I was looking at buying a project atv. he said that it burns oil... for me it is easy to change out rings, I don't have a lot experience with heads and valves. what is a quick way to determine which it is? thanks Quote Link to comment Share on other sites More sharing options...
Taillight Posted August 22, 2016 Author Share Posted August 22, 2016 sorry, can someone move this to the general forum... Quote Link to comment Share on other sites More sharing options...
stealth bomber Posted August 22, 2016 Share Posted August 22, 2016 Really no quick way to tell. Even a cylinder leakdown test won't necessarily show bad or stuck oil rings. The cylinder head has to come off to do piston rings anyhow, it would be kinda foolish to put it back together without doing a valve job and replacing valve seals. Not much cost for a machine shop to do that work if you hand them the head. Quote Link to comment Share on other sites More sharing options...
Capt.Storm Posted August 22, 2016 Share Posted August 22, 2016 If the exhaust has oil in it that's not good..nor if the air filter is oily. Compression /leak down test will tell a lot. If you put the cyl. on top dead center then with a adapter apply air pressure into the cyl you can listen at the intake,exhaust and oil sump for leaking air past valves/rings. It's not all that easy to do rings on a 4s because the valves are overhead. Quote Link to comment Share on other sites More sharing options...
stealth bomber Posted August 22, 2016 Share Posted August 22, 2016 Any oil the engine is burning will eventually find its way into the exhaust. Oil in the air filter could be an indication of too much blow by (piston ring problem) causing oil to come through the breather tube. A leak down test is very useful to find the source of the cause of low compression test. But neither a leakdown or a compression test may show the cause of burning oil due to failed valve stem seals or stuck oil rings. My point was it doesn't make much sense to do one without the other as it's pretty much just as much work. Quote Link to comment Share on other sites More sharing options...
Capt.Storm Posted August 22, 2016 Share Posted August 22, 2016 1 minute ago, stealth bomber said: Any oil the engine is burning will eventually find its way into the exhaust. Oil in the air filter could be an indication of too much blow by (piston ring problem) causing oil to come through the breather tube. A leak down test is very useful to find the source of the cause of low compression test. But neither a leakdown or a compression test may show the cause of burning oil due to failed valve stem seals or stuck oil rings. My point was it doesn't make much sense to do one without the other as it's pretty much just as much work. oh i concur..do it all at once for any oil burning...it's all apart anyways. Quote Link to comment Share on other sites More sharing options...
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