engine blowby
Another thing to check would be that the end gaps of the rings are staggered and not in line. Are the plugs getting oil fouled? With that kind of oil coming by the rings they should be. Just thinking out loud. Keep us informed of what u find.Ultimately a teardown and inspection is in order.
64' CB77
65' CB160 That's lots of good input.
The symptoms seem to indicate that there is some combustion pressure getting past the piston rings. The rings may be worn. The pistons or bores may be worn. We can only speculate as to which the issue might be. I'd speculate that the rings are worn and maybe the pistons and bores too. The time will come when it changes from desirable to necessary to strip the motor and have all the parts inspected and measured and compared to standard dimensions. The real question is when is that time. If the bike is running fine and not getting a lot of use, it can wait. If it's absolutely needed as your only source of transportation and lives depend on its availability, well that may be different. It's an old Dream and much as we love our old bikes, they are toys or at least they are a hobby and they only need to be as perfect as we want them to be. If it were me, I'd run it for the next few months while the weather stays kind and gather manuals and parts books and do the research. When the snow starts to fly would be a great time to remove the carb and pipes and wiring carefully and record it all on camera and in notes. Then I'd drain the oil and slip the motor out and strip it slowly and methodically in a nice warm garage or basement. I'd look at it this way. You spent time getting it up and running and now it's running, you have had a chance to evaluate it and now wish to take it to the next level. Fortunately, you are familiar with the bike and you got it running and these things are very simple to work on. That's my opinion. Yours may vary. blowbyThanks Teazer,
I'm going to take my spare cylinders to a machine shop and have them checked out. Hopefully I can start fresh with whatever I need. Oversize pistons and rings if needed and have them do the preparation. I'll have all that ready before I tear into again. I've been working on this thing too long to give up. It's still a great little bike and a kick to ride on country roads. I haven't pulled the plugs as it's running great.
Re: blowbyWith the top plate/cover off ya will see a metal gasket and a fiber gasket.
Did ya make sure the 2 oval holes at the edge are installed at the front of the engine?. ........lm
blowbyOK,I pulled out my extra set of cylinders. I'd like to have this ready before I pull my engine back in case there is a big problem.
The previous owner of this engine told me he installed new piston rings only a few miles before his friend crashed the bike into a stone wall. He said the engine had standard pistons. I removed the top ring from the piston that the cylinders came from. I put the ring into the cylinder and it had an end gap of about .034 -.035. The limit is .035. I'm still going to have the cylinders measured. The cylinders have very light scoring. Can't really feel anything when running my fingernail across it. Is lightly honing the cylinders a do it yourself job or should I have them professionally done? The answer usually is - It depends. If a barrel is close to stock (nominal) size and generally in good condition, and owner quick hone is probably OK with enough lubricant and care.
If the barrel is worn, it usually needs to be bored and honed by a professional to the right tolerances. If you feel confident and qualified to measure the barrels, do so, but I'd take them to an engine shop and have them measured and if they are over, or close to, the wear limit, I'd bore them the next size up and fit new pistons and rings. The first step is to have them accurately measured.
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
