Four Wheel Forum

Hi, Newbie with a question here,

I have been working on a ca95 that was a barn find, in nice condition, with less that 4k on the clock. The current owner tells me that mileage is accurate but is vague on other aspects of its history. He has never seen it run. The bike was left standing for a season and the pistons froze in the cylinders. This was caused by rust forming above the piston line and when the owner tried to kickstart the bike, the pistons jammed on the rusted sections of the cylinders. I pulled the head, freed the cylinders and reassembled the bike. Compression is 120 on both cylinders. A couple of minutes after the bike was started, lots of smoke started coming from the right exhaust. So much oil was getting into the cylinder somehow that it even started leaching from the exhaust gasket and dripping on the starter motor. I thought perhaps that oil was leaking into the head across a bad head gasket. I pulled the motor yesterday, with the owners assistance, pulled the head again, replaced the oil sealing o-ring at the head gasket locating tube and torqued the head down to 15lbs per the manual.
When I ran the bike this morning the problem is still there. Lots of oil leaking into the cylinder. I am stumped now. Compression seems to be fine. The crankcase breather seems to be working fine. Before the owner called me he said he had tried a variety of lubricants, solvents etc through the sparkplug holes and valve caps in an attempt to free the stuck pistons. Any chance this could have damaged the oil seals? If so, why do I still have decent compression? Otherwise the bike runs well...

This has the owner very frustrated with me now since this is the second complete teardown and reinstallation of the motor/cylinder head.. There is a lot of oil making its way to the head when the bike is running, ( I pulled a valve tappet cover to have a look). Perhaps an oil return line is blocked? But I'm clutching at straws....
I would reeeally appreciate some insight here.

Regards,

Gareth.

1st. Check the oil level in the crankcase. Drain the oil and measure. A totally clean motor only holds .9L (900 ml or a tad more than a quart) BUT with sludge and the like in an old motor, I would drain and replace with 800ml (a tad less than a quart) of oil.
2nd. The most likely place to get an oil leaking outside the motor is that small "O" ring at the head/cylinder match. The number one cause of an oil leak at that point is the wrong "O"ring material. The "O" ring should be GREEN (Viton) and not black. The black standard "o" ring will melt and leak.
3rd. Being that the owner may not know the history of the bike, someone may of installed one or more piston rings up-side-down. This will yeild good compression and still burn oil.
4th. Every time a motor is torn down you need a new head gasket. Painfull as it sounds, I never gamble on a used gasket, even if installed a short while ago.
5th. An oil leak outside the bike can be checked with powder foot spray used for athletes foot. Clean the engine dry. Powder spray the cylinder heavy. Start the bike while closely watching. The oil will wash away the powder where the leak is.

Thanks, Spokes, for the ideas..

The o-ring was replaced yesterday with a new green viton replacement. The head gasket was new when I first reassembled the engine. I reused it yesterday. I have torqued the head down twice now on this gasket and the motor has about 10 minutes running time on it so far. Is there supposed to be some sort of sealant used between the faces of the gasket and the head/cylinders?

Regards,

G/

I don't use sealant on the head gasket. There is a chance that you have a crack in the cylinder. Clean and powder the motor and check for a stream.

If your still dumbfounded after doing everything you can, I can send you an ounce of tracer dye. You would need a black light while in darkness to see the leak