Thanks for your help with this one.
Wonder if I could get my status changed from trainee to idiot.
Turned out the saw was a little ripper and I used it quite a bit, for small jobs where you were likely to be cutting sand. Or if somebody wanted to borrow it. Unfortunately, I initially re-attached the governor incorrectly (put the washer in last instead of first) and it damaged the housing. Didn't seem to be a problem, then the brake started seizing, again not a problem I just cut the brake band. But somewhere along the line it damaged the chain oiler. As I mentioned I was pretty happy with the saw and got a new oiler for it. Turns out you need to remove the saw from the housing to replace the oiler, I thought it would be a half hour job. Should have remembered what Tyler said earlier about those screws holding the motor in, they also hold the motor together. Finished up splitting the motor in two.
Installed the oiler and reassembled which was very difficult getting the piston in from the bottom, but would not start, wouldn't even fire. I wish I had done a compression test at this time.
I assumed that the problem was the sump gasket seal. Bought some expensive permatex gasket cement and reassembled. Had a dry run first as there was not enough room to put the gasket cement on and it went together quite well but I did not learn what I did. Put the gasket cement on and could not get the piston back in, finished up breaking the piston ring. Ryobi no longer stock a piston ring for it, so I measured the size of the pieces and determined that was the size I needed. Got 10 from China for $11.00. As you probably know they are too big. Filed one down and using the piston pressed it into the cylinder to make sure it was square and just the right size for the cylinder. Reassembled same result and compression was disappointing. As your aware there are some steps at the end of the piston ring, so I filed the next one down at 45 degrees, about this time I became aware of a pin in the piston ring groove, seems like a good starting place. Reassembled virtually no compression. Lucky I got 10 of these. Very carefully ground one side of the next one down using my imitation Dremel and replicating the other side as close as possible.
I think I may have found the secret to getting the piston back in. Have the piston ring gap on the pin in the piston ring grove and have the gap facing the exhaust port and turn it. I have enough compression to register something on my tester but below where calibrations start (50psi) plenty of spark but no fire. I am turning it over with a drill. Not even firing if you pour fuel in the spark plug hole.
One last roll of the dice, before I go to any more great lengths to get the correct piston ring, I will need to take it apart again and carefully measure the piston is there anything else that could be robbing me of compression or preventing it from firing?
Common sense would be to drop it in the bin but I don't like quitting
