26
AIR & FUEL SYSTEM
The requirements of carburetor flow rate:
■ With the flowmeter: The idle speed flow rate is 0.26-0.28 lbs./h (0.12-0.13 kg/h). The high-speed
flow rate is 0.88-0.97 lbs./h (0.40-0.44 kg/h).
■ Without the flowmeter: The idle speed is 3000+1000 rich. Adjust to maximum speed, then adjust the
H screw counter-clockwise 1/4 turn.
To adjust the carburetor, a tachometer is needed (Fig. 32). When testing the speed, the tachometer
should be placed near the spark plug of the trimmer.
NOTE:
When adjusting the carburetor, place the trimmer on a flat stable surface in an open area.
Keep the trimmer off the ground and away from any objects when making adjustments. Keep all parts
of your body away from the trimmer head.
■ Start the trimmer and run at half or low throttle for about 2 minutes, to warm the engine. Once the
engine warms up, run the trimmer at full throttle and bump the trimmer head on the grass or ground
2 to 3 times to advance the cutting line to the correct length. When adjusting the carburetor, the line
has to be at the correct length to be able to check the speed accurately.
■ Adjust the H screw: while running the trimmer at full throttle, first turn the H screw clockwise slightly
with the carburetor adjustment tool, and observe the RPM displayed on the tachometer to verify
the correct adjustment direction (clockwise or counter-clockwise) for reaching the max no load
speed. Then turn the H screw slowly in the correct direction, and observe the RPM displayed on the
tachometer until it reaches the max speed (Fig. 33).
Fig. 31
Fig. 30
Fig. 32
rpm
CLOCK SET
A
B
C
D
E
F
G
RESET
21:42
L Screw
L Screw
T Screw
H Screw
