Westfalia FM BK 55/50 Operating Instructions Manual page 85

Maintenance
acceleration and idling are achieved. Once max. acceleration is
achieved, turn the L jet 1/4 turn counter clockwise.
Fine Adjustment of the T-Idle Screw
Adjust the idle speed with the T-screw. If it is necessary to re-adjust,
turn the T-Idle screw clockwise while the engine is running, until the
chain starts to rotate. Then turn counter clockwise until the chain stops.
A correctly adjusted idle speed setting occurs when the engine runs
smoothly in every position.
Fine Adjustment of the H Jet
The H jet influences the power and the idle of the machine. A too lean
adjusted high speed (high speed needle H is turned too much
clockwise) gives over revs. This will damage the engine.
Run the engine at full speed for approx. 10 seconds. Do not run it for
more than 10 seconds! Turn the H jet 1/4 turn counter clockwise. Run
the engine again for approx. 10 seconds and you will hear an audible
difference. Repeat the process and turn the H jet 1/4 turn counter
clockwise.
Turn the H jet clockwise until the sound and setting is correct. For
optimum setting of the carburettor a revolution counter has to be used.
Do not exceed the max. speed setting.
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