Best octane to use in xs400

right that makes sense. Another thing learned

It reminds be back in the late 90s when I had a Passat turbo. Everyone was freaking out cause the manual recommended 95 octane and no one could find it and was asking if they needed to add octane booster. They finally realized that the octane rec was RON and the 91 octane here in the states would do just fine.

what is the comprssion ratio for a xs400?

9.2:1 to 9.4:1 depending on the year. I think the dohc bikes are a bit more.