An engine with an acoustic emissions valve or reflector for an exhaust system is disclosed. This reflector is disposed outside of the exhaust system—the reflector is disposed in the atmosphere into which the exhaust system discharges. The reflector is moved between a reflecting position (where the reflector reflects or obstructs acoustic emissions from the exhaust system) and a non-reflecting position (where the reflector does not obstruct the bulk exhaust gas flow from the exhaust system) by rotation of the crankshaft.