Motorcycle Repair: compression test, honda shadow vt 750, valve stem seals

Question
hello-honda shadow vt 750 1983-im need to repair the piston rings and the valve the compression test mark rear cyl 125psi and front 110psi-oil test on cylinders mark 125psi rear and 110psi front or need valve work--gama-thanks for your time

Answer
Gamalier, if the rings were worn badly the compression would jump up with addition of oil in the cylinders. The lack of major change indicates that the problem is probably more related to valve leakage. After 27 years, the valve stem seals certainly will need changing and may have been dribbling oil down the guides which causes carbon build-up on the valves and combustion chamber areas.

Check valve clearances first. If they are at specifications, then they must be leaking at the seats. If you have a shop that can do a leakdown test, that would help pinpoint the compression loss more easily and accurately.

You didn't mention the mileage on the bike, so I am guessing to a certain extent, but I would pull the heads first before tearing the cylinders off. One the heads are removed, you can take a look at the cylinder bores and get a better idea if there is excess wear there or not.

Bill Silver