DECOMPRESSION VALVE
12
28
Service
Check that the valve moves. Carbon
removing chemicals or a light oil
(diesel oil) can help a jammed valve to
work again. Blown clean the valve with
com pressed air. Carbon deposits on the
valve and the seating can be removed
using fine emery cloth.
Service
Check that the valve moves.
Clean any soot or deposits from
the valve..
Assembly
Clean the sealing washer and check that
this is not damaged before assembling
the the decompression valve.
Leakage test
The decompression valve can easily be
checked for leakage without starting the
machine. Use a leakage spray or soapy
water. Move the stop button to the stop
position and slowly pull the starter handle
while observing the decompression valve.
Decompression valve
Function
The decompression valve reduces the compression in the cylinder when
starting.
A limited quantity of fuel/air mixture leaks out through the decompression
valve, as shown in fig. A.
As soon as the engine fires the valve will close due to the combustion
pressure, as in fig. B.
A
B
Dismantling
Dismantle the cylinder cover
and the starter to gain access to
the decompression valve.
Dismantling
The cylinder cover and the starter must
be dismantled to gain access to the
decompression valve.
Dismantle the decompression valve
using an open-ended spanner or combi-
nation spanner.
Assembly
Clean and check the sealing
washer.
Leakage test
Use a leakage spray or soapy
water. Place the stop switch in
the stop position and pull the
starter handle slowly.
