Exhaust gas control means for motorcycle

Abstract From the Canadian patent

A number of embodiments of motorcycle exhaust systems including control valves for controlling the effective area of the exhaust pipes and for improving performance by preventing reflections from one exhaust pipe back into the cyclinder served by another exhaust pipe. The valve means lies under the engine crankcase and the crankcase is formed with a recess for clearing the valve means and permitting air flow across it for cooling purposes. Various calving arrangements are disclosed as is a skid plate arrangement for protecting the valve means.