Well, cruising these forum topics, this isn't going to be new to most of you, but before I start a major overhaul just wanted to throw this out there and see if anyone has any bright ideas.
I've got a 78 CB750 F2. Last year bike started burning oil during normal operation. Blue stinky smoke out the exhaust, more prevelant in lower rpms. This is after it's warm and has been running. Also, I notice it more on longer trips rather than at startup and during shorter trips. So after about 50 or 60 miles, come to a stop sign, and when I roll on the throttle, big plumes of smoke out of the exhaust.
So late last year I did a top end freshen up (hone and re-ring). All new gaskets and seals in the top end. To my dismae, it's still burning oil in the same fashion as before. All four cylinders have good compression, 160, 155, 155, 160. So makes me think the rings, and piston-bore clearances are all good. That leads me to the valves. I didn't do anything with the valves when I took it apart last year, other than clean all the carbon from the dome and valves. I did remove all of the valves and installed new valve guide seals.
Befor I pull the engine and head again, I wanted to see if anyone with more experience than me might have some ideas of what I should be looking for.
Even if the valve guides are worn, would they leak if I had installed new valve guide seals?
Is there any other part of the oil system (pump/sump) that might be faulty that would cause symtoms that would mimic worn valve guides?
Any thoughts would be much appreciated. thanks in advance for and thoughts or ideas!
Steve
