Yamaha Energy Induction System

The Yamaha Energy Induction System ( YEIS for short ) is a technology developed by Yamaha Motor to optimize the power output of two-stroke engines .

It consists of a plastic container that is connected to the intake port of the engine with a rubber hose. This creates a kind of reservoir between the carburetor and the cylinder, in which the two-stroke mixture is retained when the valve is closed (little or no gas) until the valve is opened again. At certain speeds, the system also functions as a vibration damper for the gases oscillating between the combustion chamber and the carburetor.

The YEIS results in better engine response, more torque in the lower and middle speed range and up to 10% lower consumption.

YEIS has been used on the following Yamaha motorcycles:

• DT 80 LC and DT 80 LC II
• DT 125
• Yamaha TZR 50
• DT 200 R
• RD 80 LC and RD 125 LC
• TDR 125
• TZR 80 and TZR 125
• RXS
• IT 490 and YZ 490

literature

• Helmut Werner Bönsch: The high-speed two-stroke engine . Motorbuch Verlag, Stuttgart 1997, ISBN 3-87943-800-5 .