Stihl 064 - Page 87

STIHL 064, 066 87
11.8 Tank Vent
Prying vent connector off stub
- Run engine at a full throttle and Corrections to high speed ad-
slowly rotate high speed adjust- justing screw with LED (066)
ing clockwise until tachometer
indicates 12,000 rpm. - Adjust idle speed correctly.
- Allow engine to return to idle - Carefully screw the high speed
speed. adjusting screw down onto its
seat.
- Rotate high speed adjusting
screw another half turn clockwise. - From this position, back off the
high speed adjusting screw exact
Note: This is the optimum setting ly two full turns.
of the high speed adjusting screw
under the barometric pressure and - Start the engine and allow it to
climatic conditions at the operating warm up.
site.
- Run engine at a full throttle and Correct operation of the carburetor
With the carburetor adjusted in slowly rotate high speed adjust- is only possible if atmospheric
this way the engine speed at full ing clockwise until the LED lights pressure and internal fuel tank
throttle may reach the cut-off up. pressure are equal at all times.
range of the governor. As the This is ensured by the tank vent.
tachometer uses the firing pulse - Allow engine to return to idle
to measure engine speed, it can, speed. Important: In the event of trouble
at full throttle, indicate a speed with the carburetor or the fuel sup
which is much lower than the true - Rotate high speed adjusting ply system, always check and
maximum rpm. This is due to the screw another half turn clockwise. clean the tank vent.
fact that the engine does not fire
on every revolution when it is Note: This adjustment can be car- - Remove the air filter - see 11.1.
running within the operating range ried out with a tachometer if the
of the electronic speed governor. LED fails. - Remove the vent connector from
Note (064 only): If the amount of the stub on the tank housing.
adjustment travel left on the high
speed adjusting screw, after set- - Pull the vent hose out of the bore
ting it to 12,000 rpm, is much less in the carburetor box.
than one half turn, the fixed jet
"64" can be installed in place of
fixed jet "68" - see 11.5.