1. Are the ring grooves clean enough?
2. piston condition remain still usable? I hope so as I don't plan to change them and in any case the engine was running fine with them in.
3. Any order/matching in ring gap dimension or we just don't care?
4. I cleaned and removed any gasket compound (used on top of paper) surplus and removed everything I can see. Is it quite critical given the oiling system to have a real clean engine interior or is it tolerant. I mean do I need to make 200% sure nothing is left behind that may plug the oiling system. Not sure of the pression and size of ports in this system.
5. any comment?
Hi Eric,
1. Probably
2. They look OK, but the critical issue is the fit of each piston to its cylinder. Check there is more than 6 and less than 10 thou between the skirt of the piston and the cylinder wall at the bottom of the stroke. I assume the bores are ok - not too badly worn at the top. If there are any scuff marks on the pistons, smooth them off with a "flat" file - preferably a brand new one that has never been used on steel.
3. Personally, I think 4 rings per piston is way too many in a bike like this. I'd use plain rings in the top two grooves and leave the others empty. Not everyone will agree, so if you want to fit more use the order proposed above. Use the smaller gaps on the top rings, and the shockers on the skirt. The ring gaps should be set by filing, rather than cutting. Make sure - with a file - the ends of the rings are square and free from burrs.
4. Clean is good. If you have sand/glass/abrasive blasted anything internal you will need to clean, clean and clean again. A few tiny floaties of gasket material won't hurt, but if you wash thoroughly most should be gone.
5. Comment: If you don't have a copy of Radco's "Vintage Motorcyclist's Workshop" get one. It has most of the answers to our questions, and contains almost nothing that is "wrong". I like the way Radco recognises that we're not trying to build MotoGP racers, and cuts some slack to the home mechanic!
Cheers
Leon