20
User Manual
21
Problem
No fuel is drawn from the tank to the carburet-
tor
Carburettor is pumping fuel OK, but engine doesn’t
start. Spark plug is wet.
Carburettor is pumping fuel OK, inlet valve is OK, but
engine won’t start
Engine starts, but won’t run at high speed
Engine won’t start, no spark in the spark
plug
No spark even after change of spark plug
Emergency breaker circuit OK, but still no
spark
Carburettor seems OK, but engine power is reduced
and engine runs erratically
If the start sprocket doesn’t react
If the engine starts and then stops immediately
Check
Check that there is fuel in the tank
Check for leaks in the fuel hose or its connections.
Check if the inlet needle valve in the carburettor is
stuck. You can open it by pressing down the main
diaphragm with a 3 mm wire through a hole in the
cover over the main diaphragm
Change the carburettor pump diaphragm and the
gasket
Check the inlet needle valve function. Is the valve
stuck in open position? Is the inlet needle valve spring
broken? Replace inlet valve and spring when neces-
sary
Check setting of low speed jet. Normal setting is 1
turn open from closed position
Clean inside of carburettor
Check if high speed jet is open. Clean jet if necessary
Change the spark plug
Check emergency breaker circuit. In OFF (running)
position the contact on the ignition coil must not be
connected to ground
Change the complete ignition unit (ignition
coil)
Check piston rings. Normal service life is 200 hours,
but can be reduced if no proper air filter has been
used
Check crankshaft sealing rings. If rings are leaking,
operation at both low and high speed is affected
Too low power voltage in the battery or too small
diameter of the cable.
Can depend on dirt in the decompression valve or in
the reverse valve on the vacuum hose to the cylinder
Troubleshooting
