I have a 87 cbr600, consumes oil at a considerable rate. Took the engine out of the frame and disassembled cylinder head, block and pistons and found there is a thick layer of cooked-on oil over all sixteen valves. I figured the oil consumption was due to bad rings, but could it have been the valves?
Do you remember when and how it smoked? If it smoked when you first started it but for the most part nothing else it would be the valve guide seals. If it smoked all the time it would be the rings. If it smoked during deceleration it would be the intake valves/valve guide. If it smoked during acceleration it would be the exhaust valves/valve guides. Hope this will get you looking in the right dirrection and good luck.
just rebuild it since you have it a part 87 im sure that among other things was the problem im sure it was both
Yep! I'd do the rings too! Pish posh on bravery, if you have the manual, anything you break is replaceable!
I'm guessing the motor was running some blue smoke out the exhaust especially at start up. And I'm guessing it was probably a combination of rings and valves. She's twenty years old. Worn rings allow oil to escape into the combustion chamber from the underside of the piston and worn valve guides/seals allow oil to be burnt away from the top. When the guides/seals become worn or dry from age they allow the oil to leak down the valve stem. That's why you will notice them being worn especially at start up. While the bike sits it gives the oil a chance to pool at the edge of the valve to head surface so when the valve is first opened a accumulated amount of oil to enter the cumbustion chamber.
Valve guides and seals will, but not the valves. Bad valves will lower compression on the engine and reduce performance but won't burn oil. The deposits on the valves are most likely from oil burning, getting to the heads past the piston rings. The rings aren't hard to change if you already have the head off... pull the cylinder block off and the pistons will be accessible. Getting the block back on can be tricky as you have to get the rings compressed. Might take two or three people. Good luck. Reassembly is harder than disassembly, but you probably already know that. Make sure you get the cam marks exactly right!
