A motorcycle is provided having front and rear wheels. A chassis is supported on and connected to the front and rear wheels. An engine is mounted to the chassis and includes front and rear cylinder heads joined to an engine block. Front and rear mounting assemblies are provided for mounting the engine to the chassis. The rear mounting assembly includes a pair of laterally spaced-apart support plates secured between the engine and a top frame structure of the chassis. The support plates are disposed rearward of the rear cylinder head. A radiator is mounted to the chassis. A thermostat is connected between the engine and the radiator and is operable to control coolant flow from the engine to the radiator. The thermostat is disposed between the support plates.