What is the expected compression reading on a 75 Norton 850 with stock everything? The motor has 12,000 easy miles on it and has never been apart. I read somewhere that 145 psi is typical. I read elsewhere that 100 psi is OK. Who knows for sure?
#1. "RE: Compression Check on a 1975 850" In response to Reply # 0
135-145 is what I have gotten on the stock 850's Ive been involved with. If you are not skilled on kicking over a big twin then you will see it register artificially low. I have seen this several times. Big guys used to electric start bikes that could not kick them over fast enough to get a sufficient spin and were able to register only 70-80 lbs. Then when I kicked I got the required 140psi.