19
SRM-4300
Carburettor adjustment
CAUTION
Cutting attachment must not turn when unit is idling.
Every unit is test run at the factory and the carburettor is fi ne tuned for maximum
performance.
Any change from this setting should be performed only with the aid of an accurate
tachometer (see Specifi cation for r/min setting).
If carburettor adjustment is performed without a tachometer, only the Basic Setting
adjustment is recommended.
Before adjusting carburettor, clean or replace air fi lter, start engine and run several
minutes to bring it to operating temperature.
Idle speed adjustment
Turn idle speed adjuster clockwise until cutting attachment begins to turn, then turn
screw out anticlockwise until cutting attachment stops turning.
Turn screw out, anticlockwise, and additional 1/4 turn.
Basic setting
NOTE
DO NOT over tighten (L) / (H) adjusters.
Forcing them to tighten will damage the carburettor.
1. Stop engine and turn both low (L) and high (H) speed mixture adjusters in,
clockwise until they stop and are lightly seated.
2. Turn low speed mixture adjuster (L) out, anticlockwise 1 and 1/2 turn.
Fine tuning
(Requires Accurate Tachometer)
1. Start engine and allow to run at high idle until warm.
2. Adjust idle speed if necessary (2500 to 3000 r/min).
3. Always begin fi ne tuning with low speed mixture adjuster (L).
4. Slowly turn (L) adjuster clockwise, try to reach maximum idle speed.
5. Turn (L) adjuster anticlockwise 1/8 to 1/4 turn.
6. Turn idle speed adjuster clockwise until cutting attachment begins to turn.
7. Turn idle speed adjuster anticlockwise 1/2 turn or until cutting attachment stops.
High speed adjustment
NOTE
• Improper high speed mixture adjustment can result in lean operation and
consequent severe engine damage.
• Do not run engine on full throttle longer than 5 to 6 seconds during high speed
mixture adjuster (H) adjustment to avoid damage to engine.
• The engine will overheat when the high speed mixture adjuster (H) is adjusted to
the lean condition reducing engine life.
1. While engine running at full throttle, turn (H) adjuster slowly clockwise until engine
runs smoothly under no load.
2.
Turn (H) adjuster anticlockwise 1/8 turn to obtain optimum fuel for full power under
the load conditions.
3. After the high speed adjustment has been completed, and should the engine
hesitate during acceleration from idle to full throttle, turn (H) adjuster anticlockwise
until smooth acceleration is obtained.
Make sure that the fi nal engine speed does not exceed 11000 r/min.
T: Idle speed adjuster
L: Low speed
mixture adjuster
H: High speed
mixture adjuster
Summary of Contents for SRM-4300
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