A scooter-type motorcycle comprising of an engine with a cylinder axis line of an engine main body tilted forward

Abstract

To reduce the length of a secondary air supply passage from a secondary air control valve to an exhaust system of an engine, and simplify piping arrangement structure by disposing the secondary air control valve sufficiently close to an engine main body, in a scooter-type motorcycle in which a power unit composed of the engine, and a transmission for transmitting an output of the engine to a rear wheel is swingablly supported by a body frame, and in which the exhaust system with an upstream end provided with an air cleaner disposed on an upper part of a transmission case for housing the transmission is connected to an upper Side face of a cylinder head. The secondary air control valve 35 for controlling the quantity of secondary air supplied from the air cleaner 27 to the exhaust system of the engine, is disposed on a side of intake passage forming means 26, in front of the air cleaner 27 and above the engine main body 19, with at least one part overlapped with the intake passage forming means 26 in side view.