Whip!
Member
Can anyone explain to me the theory/function of the exhaust valve. The servo controlled cable operated one at the bottom of the header. I guess the engine likes a little back pressure under certain conditions. What are the conditions that open and close it? Based on RPM I'm assuming. Or start up, I dunno. Is it incremental, or more like an on/off situation. Just curious. I installed an aftermarket exhaust on an R6 for a guy a little while ago that omitted this part. It seemed to start a little harder after that.... on an EFI bike.