how can i tell if the rings are shot on xs850sh yamaha 1981?

Question

It did blow white smok the last time i rode it but oil came shooting out of exhaust@connection 2 head and new spark plugs oil and carbon on them. was there to much oil or did the rings blow

Answer 1

If the rings are so bad oil came out of exhaust its unlikely that it would even run. You probably have a fuel problem. The valve guide seals may be damaged, particularly exhaust side which would allow it to run Ok ish but produce a lot of blue/white smoke.
If its just white its usually condensation from exhaust. Black is excess fuel. Too high an oil level or a blocked engine breather will cause cases to pressurise and give same effect, usually with oil leaks from seals.

Answer 2

The rings in my XS11 were pretty worn a few years ago, and Yamaha still had new ones available. Not bad for an 80 bike.
The only way to know for sure what's wrong is take off the head. You can check for cylinder wear and get a good idea of ring wear by looking at the ring gaps. I bet your cam chain is at the end of it's adjustment and in need of replacement if it's the original, so that would be a good chance to get everything at once.
Of course, you'd have to pull the cylinder off to check the oil ring, but you can do all that stuff while the engine is still on the bike with your model, so it's not too bad.

Answer 3

I agree with the compression test answers, to check for piston & rings and cylinder wear. That should be the first thing you should check (after making sure that the crankcase isn't over filled with oil). If the valves were leaking, that wouldn't cause the exhaust to smoke or the plugs to foul. In all my years of repairing motorcycles, I've never seen valve seals leak, unless the engine was in serious need of repairs.

Answer 4

I agree, run a compression test, but on 4 stroke engines, it could tell/be confused with valve leakage.

Answer 5

your best bet is to run a compression test.