MOTOBRICK.COM
TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => The Motobrick Workshop => Topic started by: cbrazbox on February 16, 2017, 06:25:59 PM
-
So I definitely have an issue with cyl 3, it came up about 15 psi lower than the rest when doing the compression test. Did a valve clearance check and adjustment recently, cyl 3 exhaust valve was .05 tighter than spec... Other exhaust valves were still within spec, but a little on the tighter side... intake valves were dead on. All were adjusted back to spec. Haven't put oil in cylinder to determine rings or valves yet.
Anyway, I notice exhaust smoke coming from where the exhaust manifold meets the head until bike is warmed up (no weird colors or anything). Theoretically, if the copper gasket on cylinder 3 is not doing its job, couldn't this cause low compression on that cylinder? (As opposed to a hole/leak in the manifold itself). Trying to avoid getting too deep into it at the moment, but if that was all it was I can find time to knock that out quickly. Otherwise I'll have to sideline it for a while until I have more time, (and miss the one week of great weather we're about to have here).
-
A compression test measures the ability of the piston rings, valves and gaskets to seal the combustion chamber for optimal compression. The exhaust manifold is separated from the combustion chamber until exhaust valves are open, so the condition of the manifold's gaskets have no effect on combustion chamber compression.
-
what he said. exhaust gasket condition had no effect on compression.
-
If the bike has been sitting for a long period rings can gum up, sometimes causing lower compression and/or blue smoke. If this is the case put some mileage on it, at least a couple of thousand miles and recheck. With more mileage it could rectify itself. As stated many times idleness is a bricks worst enemy. :riding:
Regards Martin.
-
Oh wait... Duh... Because exhaust valves. I honestly don't know what I was thinking the other day. I guess sleep deprivation has more effect than I realized. :falldown: Thanks for reality checking me before I wasted energy on something pointless.