ATC 185s oil in exhaust.

[81ATC185S]

I have a 81 ATC 185s that was smoking really bad, I put new valve guide seals in thinking that was the problem and I reassembled the engine. I did a compression test and it checked out a little low but good enough and I had no exhaust when I bought the bike so I threw a straight pipe on it. It started up fine no smoke then it ran for a bit and slowly oil started pooling out of the exhaust. Like actual oil not just mist, I am talking FULL ON ACTUAL STANDING OIL in the exhaust. Any ideas on what the cause could be?

[tri again]

185? Vertical engine?
Oil in exhaust pipe, and not the airbox?
Does it seem to run ok other than that?
Not sure if it has a decompression lever or that even matters.

Any chance the valve seal come loose?
The search key has been working great these days so maybe try some keywords like
'oil in exhaust' or oil exhaust, and don't be afraid to read posts even if it's not your specific machine.

Pls let us know what you find.

[DohcBikes]

What were your compression numbers? Is there oil on the spark plug?

[81ATC185S]

Compression numbers are about 150 and there is very slight oil on the plug ill tear into it today.

[3wheelrider]

Compression numbers are about 150 and there is very slight oil on the plug ill tear into it today.

My guess is its missing the o-ring on the rear cyl.stud. Or the o-ring is damaged...
With the angle of the cylinder-oil will seep back into the cylinder instead of seeping outwards(outside)
?????.

[81ATC185S]

Yeah I don't think it actually has oil out the exhaust. it just smokes like a vapour and then pools in the exhaust. I think I need new rings because it has a new head gasket as well. I didn't replace the rings or hone it when I had it apart because I am no mechanic but I thought the cylinder walls looked pretty good. They probably aren't good enough I guess.

[Gearheadtom]

The cylinder/piston might look good, but could not measure in spec. The best way is to have the cylinder measured, see how far oversized it needs bored, new piston, gaskets, etc..., but hone the cylinder a little, new rings, new head gasket, and it'll probably be alright.