Automatic Decompression - Robin DY23-2D Service Manual

6- 6
AUTOMATIC DECOMPRESSION
SYSTEM
The decompression system operates to release compression by lifting up the exhaust
valve at starting.
, "
The release lever mounted on the camshaft has a flyweight a t one end and a crescent
cam at the other end. When starting the engine, the crescent cam juts out from the
exhaust
.
cam.
The exhaust tappet rides
over the crescent cam opening the exhaust valve to
release
compression.
CRESCENT
EXHAUST
FLYWEIGHT
C A M
C A M
TAPPET
2LtL l /
RELEASE LEVER
/
EXHAUST CAM
SNAP RING
CAMSHAFT
FIG. 77
, - -
When the crank speed reaches
a
certain revolution, the flyweight
of the release lever
moves outward by the centrifugal force turning the release lever to retract the crescent
cam. Thus the exhaust valve closes allowing a sufficient compression for the engine to
start up.
'FLYWEIGHT
LEASE LEVER
SNAP RING
CAMSHAFT
FIG. 7 8
The components of the decompression system are different
by " D " type and " B " type
engines, however the principle of operation is the same.
/
- 50 -