What is the factory recommended fuel octane for a 1982 VF750 S Sabre? I am bringing the old bike back to life which has been parked in the back of the garage unused for years. I don't have the owner's manual and the Clymer's Service Manual does not specify the fuel octane. I seem to recall filling up with premium when I was still riding it 10 years ago, but I would like to verify that premium, 91 octane, is recommended.

Any knowledgeable input is greatly appreciated.