Yamaha Hatsudoki Kabushiki Kaisha

Yuusaku Yamaoka

Toshimitsu Iio

A water-cooled two stroke engine including a cylinder formed with an exhaust port which is adapted to be cyclically closed by a piston reciprocating in the cylinder. The exhaust port is provided at the upper portion with a port timing control valve which is operated to control the port timing in accordance with the engine speed by a piston-cylinder type actuator. The actuator is adaped to be operated by the engine cooling water pressure and has an operating pressure chamber at one side of the piston and a compensating pressure chamber at the other side. The cooling water supply passage has a flow restriction and the pressure upstream of the restriction is introduced into the operating pressure chamber and that downstream of the restriction into the compensating pressure chamber.

Growing community of inventors

Iwata, Japan

Yuusaku Yamaoka