c92 oil from top of engine

Greggie-e · Post by **Greggie-e** » Sun Nov 23, 2008 5:55 am

My C92 is throwing a lot of oil out of the breahter at the top of the engine.
I have not split the engine as both cylinders have 10:1 compression. So I have assumed that the vlaves and the rings are alright.
Is the bike supposed to be pushing a bit of oil out the top?
The breather tube is supposed to feed back into the airfilter, I am pretty sure that it is not supposed to be throwing so much oil out, but cannot think why it would be doing it.
It is not overfull, and still does it with low oil?

Any ideas?

Greggie-e · Post by **Greggie-e** » Thu Nov 27, 2008 1:14 am

I am thinking that there might be a fault in the "oil Seperator" that sits before the breather, has anyone had any issues with this beofre?

Greggie-e · Post by **Greggie-e** » Tue Dec 09, 2008 12:27 am

Nope not the seperator.
I am suspecting a cracked ring, despite the high compression.

Out with the engine....

3BeanCrispy · Post by **3BeanCrispy** » Tue Dec 09, 2008 3:46 pm

wish i had some info to help, just curious about the outcome. keep the updates comin' please! and best of luck ... hope the problem is minimal for ya

Greggie-e · Post by **Greggie-e** » Tue Jan 27, 2009 11:29 pm

Well I took the engine out and the head off.

There is practically no wear on the bore, none of the rings are broken, and the valves seem to function properly.
I am a bit stumped.

I am going to examine the oil pump to see if it is perhaps pumping too much somehow.
Is it possible that I put it in incorrectly and it is directing too much oil to the top of the engine?

Since the head os off I might put a mild cam in, you know, just in case...

Greggie-e · Post by **Greggie-e** » Thu Jan 29, 2009 11:29 pm

it was getting some crank case pressure, so I am thinking it might be the valve guides or it could be that the rings were put in upside down or did not bed in properly...

Has anyone had any cases where they get crank case pressure from a glazed bore?

Greggie-e · Post by **Greggie-e** » Thu Feb 05, 2009 7:27 pm

After swearing a lot trying to find out what the issue was I took it to a mechanic who works with vintage car engines a lot.
He took a look at the barrel and noted that there was water damage to the surface, lots of tiny little pits.
I am assuming that this is causing the crankcase pressure and thus the oil from the breather.
So I have ordered some dodgy Thai pistons (0.75 as it is currently at 0.50) and will try a re-bore to see if that helps.
While the top is off I am going to jazz the cam up a little. Only a little though.

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c92 oil from top of engine

c92 oil from top of engine