I just put a 11:1 compression piston, stage 1 hotcam, and a full FMF Titanium 4 exhaust on my 2000 Honda 400ex and I am unsure about how I should jet the carb. I would like to have the jetting pretty close before I even fire the engine up for the first time. Does anybody else out there have a 400ex with similar mods that could tell me how to jet it? Should I run race fuel because of the high compression piston?

 

You can run 91 or 93 octane with the high comp piston. Try a size or 2 larger in the main jet than normal jetting specs for the titanium 4.