McCulloch T22LS Workshop Manual page 27

Fine adjustment
Fine adjustment of the carburettor should be carried out after
the engine has been "run-in". It is important that the air fi lter is
clean and that the carburettor cover is fi tted when adjusting the
carburettor.
The engine must be run warm at full throttle which is approx.
11,000 rpm (electronic speed limitation). Run the engine for 4 to
5 minutes to make sure it is warm.
Then adjust the carburettor needles in two steps as follows:
First adjustment
1. Turn the L needle clockwise until the top idle speed is
reached. If the trimmer head then rotates, reduce the speed
by turning the idle screw (T) anticlockwise until it stops rotat-
ing.
2. Turn the H needle at full throttle to the position where the
engine starts running as a 4-stroke.
3. Stop the engine.
Second adjustment
1. Start the engine (still warm).
2. Turn the L needle anticlockwise so that the speed drops by
500 rpm.
3. Stop the engine.
4. Turn the H needle a 3/4 turn clockwise.
5. Then adjust the idling speed to 2,900 rpm by turning the idle
screw (T).
Fuel system
Basic setting
The carburettor is set to its basic setting when test run at the factory. The basic setting
is "richer" than the optimal setting (fast idle speed is 600–800 rpm under the recommen-
ded max. speed) and should be kept during the engine's fi rst working hours. Thereafter
the carburettor should be fi ne tuned.
The basic setting is: H = 1 turn open, L = 1,5 turns open.
530 03 55-60
Both of the high and low speed jets in the carburettor can only be adjusted using the
special tool 530 03 55-60.
To carry out adjustment when replacing needles or the entire carburettor the engine
must be under load. This is achieved by fi tting a standard trimmer with the specifi ed
length (defi ned by the blade on the trimmer guard) and diameter of the trimmer cord.
Consequently, the stated speed will be much lower than with "normal" carburettor ad-
justment when the engine may run freely.
After replacing the needles or the entire carburettor on a CARB-EPA approved engine,
adjustment must be carried out according to the instructions below.
The combiguard or trim guard must be fi tted when adjusting the H-needle.
NOTE!
If the cutting equipment rotates while idling, the T-screw
must be turned anticlockwise until it stops rotating.
A tachometer should always be used to fi nd the optimal
setting.
Idling speed T-screw
Let the engine idle for about 30 seconds or until the speed has
stabilised. Adjust the idling speed T-screw until the engine idles
without stopping.
• Turn the screw clockwise if the engine stops.
• Turn the screw anticlockwise to lower the speed.
Correctly adjusted carburettor
A correctly adjusted carburettor means that the engine accele-
rates without hesitation and it four-strokes a little at full throttle.
•
•
•
•
502 71 14-01
The cutting equipment must not rotate while idling.
A too lean adjusted L-needle can cause starting diffi culties
and poor acceleration.
A too lean adjusted H-needle results in lower power, poor
acceleration and/or damage to the engine.
A too rich setting of the "L" and "H" needles give accelera-
tion problems or a too low working speed.
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