Bike is 1959 Dommi '99'
Just completed a full engine rebuild and, after about 15 miles of running, I have two problems.
Oil is being blown out of my crank case breather. I'm not sure how much, if any oil, should come out but it seems rather too much to me. Does this mean something has been assembled incorrectly during the rebuild, or is there a more obvious cause that is addressable without taking the engine down again ? Please say YES !
In addition I have an oil leak from the cylinder head. Reading this up on forum it may just be that I have to keep tightening the head down. However, it also may be the wrong choice of head gasket. I've fitted one which I believe is known as 'composite' i.e. 2 sheets of thin copper with a material between them. What is a 'halite' gasket and what is a 'flame ring gasket' ?
Thanks in anticipation,
Hello Mike - Did you fit new pistons, rings and have a rebore during your rebuild ? If so it is not uncommon to get some oil out of the breather until the rings are bedded in. If not you may have a more serious problem. You could attach a piece of clean tubing to the breather pipe exit at the rear of the crankcase and slowly turn the engine whist blowing down the tube. On each stroke you will feel the pressure free and then blocked as the camshaft timing disc rotates. Usually oil out of the breather signifies pressure getting past the rings - or the breather is not engaged. I presume the compression feels ok using the kickstart ? Buy your cylinder head gaskets from a reputable spares supplier. The composite copper/asbestos sandwich types are fine on a 99 assuming that you still have a lip on the mating surface of the barrel. Hallite metallise fabric types were used when the lips went on the 650SS and Atlas. Isn't a flame-ring something that follows a really hot curry ? Apologies to sensitive readers and Curry lovers. Cheers, Howard
Hi Howard - yes, a complete rebuild. Crankshaft reground, new big ends and mains, rebore, new pistons, new conrods, etc. New cam shaft bushes fitted, but used same breather valve on end of cam shaft but with new spring. The compression is amazing. Can stand on the kick start indefinitely !
Thanks for your response. I'll try blowing down the breather pipe and stick with my composite head gasket.
Just off for a curry,