Automatic Decompressor - Yamaha F4B Service Manual

TECH
FEA
Technical features and description

Automatic decompressor

To facilitate engine cranking, the decompression actuator forcefully opens the exhaust valve on the
compression stroke to release compression pressure during engine cranking and prevent pressure
in the cylinder from increasing. As the cranking speed increases, the decompression actuator will
move in the direction of a due to the centrifugal force and the exhaust valve will return to normal
operation.
a
Decompression actuator
A
A Compression pressure
2-5