Bought a 1974 R90/6 this summer. Just a little clean up, some electrical issues, cleaned up the carbs, new battery and it's running strong and starts easily. Did a compression test and was surprised to find both sides in the 80psi range. A I doing something wrong, or can a reasonably well performing bike have compression that low?
Rode it for about 15 minutes. Disconnected and removed both plugs. Placed caps where they wouldn't ground. Twisted the throttle wide open and cranked it over. Both sides about the same, 80ish psi. I read 120 or so means a bad engine. What's up???