Service Manual

COMPRESSION RELEASE SYSTEM
This engine has a compression release system that,
decreases the amount of effort required to start the
engine and reduces engine run-on when stopping
(Figure
11-18).
The system works as follows:
1. As the engine is started, a spring holds in the
flyweight, which in turn pushes a decompres-
sion pin upward.
2. The decompression pin pushes up on the
exhaust tappet and opens the exhaust valve
momentarily to release compression and make
starting easier.
3. As the engine speeds up, the flyweight is
forced outward by centrifugal force and the
decompression pin moves down
so that it no
longer opens the exhaust valve.
4. When the engine is stopped, engine speed
drops and the flyweight pulls in and the decom-
pression pin moves up. The pin opens the
exhaust valve again releasing compression.
The most common problem with this system
is a
faulty spring. The spring may be too long
or it may
not be connected.
A spring that is too long will re-
duce the decompression cutoff
speed. Make sure
the spring is properly attached,
if a problem with the
cutoff speed is suspected, replace the spring.
CAM GEAR
I
ENGINE START POSITION
TAPPET
FLYWEIGHT
CT-1121.
FIGURE 11-18. COMPRESSION RELEASE SYSTEM
11-11