Reese ,
While I was cutting a new gasket for the compression plate , I noticed that the plate didn't want to settle nicely onto the motor case mating surface . Taking a closer look , the plate and the mating surface were not meeting as they should . The plate was slightly bent and the motor mating surface seemed a bit higher toward the outside of the 'circle' . Using the best straight edge I have ( a high quality dial caliper ) , I confirmed that I was right . I carefully used my best flat file to level the surface , double checking with the caliper edge as I progressed . Once satisfied it was as level as I was going to get it , I laid the plate in place and tapped it into a more correct form . At least now a gasket would be able to do it's job .
That process had me looking farther . I checked the motor carburetor mount and found a similar situation . I flattened the mount and test fit the carb in place only to find that the carb mounting flange was wrapped to the point that a gasket would have done absolutely no good at sealing the joint ( also confirmed by the caliper edge ) . I took the carb to the belt sander and rough leveled the mating surface , finishing the job with the flat file and a check with the caliper edge of both the motor carb mount and the carb flange mounting surfaces . Now a gasket is hardly needed , but I'll use one just because I already have one cut .
What really puzzles me is the fact that I rode the bike with this motor and carb 47 years ago . How it ran then , I have no idea .
Anyway , all this somehow reminded me of your motor running poorly and I thought that possibly you might have the same type things causing your motor problems . You said that you checked everything else . Did you check these things ?
