I have a friends quad over at my house where we are working on it. It sat for about 5 years until last year when he got it out got he carb cleaned, replaced the plug, and started to ride it...Once. The second time he rode it, it just cut out in the middle of riding and would not start again. We have been going through all the simple issues when we pulled the plug and the inside was completely covered in oil. On the business end. From what I have read is more than likely a bad piston or piston ring. I was wondering if any one has ran in to this before and if there anything I should know before taking a engine apart for the first time.
Thanks

 

It didn't smoke any before this happened? Any noises just before it quit?

If the inside was "covered" with oil, and it suddenly quit, I'd be leaning to something a little more catastrophic than a leaking gasket or rings.

Unfortunately, you've got oil in a place it shouldn't be. Taking it apart sounds like the only way to find out why.

 

Probably needs to come apart, I agree.

Before doing that, I'd be curious if it has any compression.

If you have a borescope, maybe take a peek for anything obvious. Not sure if Auto Parts stores loan out borescopes.

If it were a 2 stroke, I'd suspect the main jet wasn't entirely clean or some gunk got in there causing it to run lean and melting a hole in the piston. Not sure if 4 strokes can suffer such.

 

Ya I was hoping it was not something catastrophic in the engine. I guess I dont know if covered was the right word. The inside of the plug was coated but not dripping or any crazy amount of oil like that. I do think i have compression because it still sounds like the engine is trying to crank at the right speed ( I was told lack of compression will cause an engine to crank like there is no resistants at all) so I don't think it is that. I will try to get my hands on a borescope and compression tested to check on both of those things.

 

My guess is that it stuck the rings in the piston.
I would see if I could get some carbon cleaning solvent down the plug hole and let it sit for a few days or so.

 

We just pulled the head cover off and looked down the plug hole and can see oil on the top of the piston head if thats helping anyone figure out the problem.

 

Only way oil usually gets there is to bypass the rings