Alright guys. I rebuilt my top end today. Got everything back together. Started on the second kick idled beautifully. I was letting it idle to get the warm to re torque the head. Then it started to smoke! BAD. next thing I saw oil blowing out around the exhaust outlet on the cylinder. Then I noticed oil blowing out around the rubber bit on the outside that goes into the oil tank. It seems like the oil isnt getting back to the tank. We've been over the wt sumping issue before. But letting it run to see if its gonna suck the oil out wont work as its blowing out around the rubber hose that goes back to the tank. Whats the expert opinion? Rings not doing there job? Oil return clogged? I immediately came here for a post. Im a bit wore out and need to rest before I grab hold of a spanner again.

email (option): micran1234@yahoo.com

By the way. The bike never stopped running the whole time this was happening. It literally blows my mind that the thing ran so nicely with oil blowing out the exhaust valve and a cloud that killed every bug in my county.

email (option): micran1234@yahoo.com

Hi Michael...I'm assuming oil is bubbling from the return line (the outer one) It is possible the return pipe in the tank is blocked. Open the lid with the engine running and remove the spring loaded cap from the oil filter..you should be able to see oil issuing from the upper end of the return pipe. If you can't, remove the return pipe from the engine to the oiltank and poke a welding rod or similar all the way up the pipe. It won't come out at the top as the end of the pipe is blanked off and it is 'cross drilled'...the rod should go up the pipe approx. 6". You can also give it a blast with compressed air if you have it. Also check the return pipe from the engine to the oiltank is clear while it is off. When you are sure both pipes are clear, replace the oil pipe and restart the engine to test. If you still don't get any oil return you'll be looking at the oil pump and drive next....Ian

email (option): ian@wright52.plus.com

I should have been more specific. Oil is running out at the rubber bit on the end of the metal return pipe at the oil tank. I feel rather confident that something is blocking the oil return pipe at the end nearest the oil tank. I didnt see alot of oil returning to the tank. Many thanks for the pointers. I will remove the oil return line and see what we have. I am guessing that it could be a blockage anywhere between the return pipe in the tank that lets the oil out in the top of the filter and the bit that goes into the rubber line. Somewhere between there pressure is building to a point that the oil is coming out at that first metal connection on the rubber bit at the tank. I will report back soon. Many thanks Ian

email (option): micran1234@yahoo.com

Well I wasnt able to get the wire very far at first and I kept at it. It went about 4 inches. i put the line back and started her up and the blowing oil and most of the smoke went away. Oil is returning to the tank now. With the filter removed how should the returning oil return? Should it shoot across the tank out of the two counter drilled holes or just sort of push out and run down the pipe? Also what have you found to be the best way to break in the new rings? Cheers. Im pretty happy with the results so far.

I did manage to get the head gasket sealed better than it ever has been too.

email (option): micran1234@yahoo.com

The oil return just trickles down the pipe at low engine revs...if you rev the engine up you will get a stronger flow but not anything like enough to shoot across the tank...a 'weak, short, jet' would be an accurate description... Once the crankcase is cleared, as it will be eventually in a dry sump engine, the return is of a 'spit and bubble' character as there is not a constant supply of oil to be returned..For breaking in rings (if you haven't had a rebore) just drive 'sensibly' for 100-150 miles....Ian

email (option): ian@wright52.plus.com

Well after a bit more tinkering and a warm up and retorque again of the head bolts... No smoke at all. Starting on the first kick everytime. Sounds great. I am so bloody happy. Many many thanks to everyone who has helped along the way. i know it wont be long before I will need a rebore and do this all over again . But I should be good for another year. This forum has really make owning an m20 alot of fun! Cheers. (oh magically after sitting the lights stopped working...)

email (option): micran1234@yahoo.com