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502 71 14-01
501 60 02-03
Fuel system
Correctly adjusted carburettor
A correctly adjusted carburettor means that the engine
accelerates without hesitation and it “splatters” a little at full
throttle.
• A too lean adjusted L-needle can cause starting difficulties
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.
NOTE!
If the cutting equipment rotates while idling the T-
screw should be turned anticlockwise until it stops.
Carburettors in E-Tech and CARB-EPA designs (CARB II-EPA II only
applies to USA and Canada)
On these types of carburettor the H- and L-needles can be adjusted within ex-
tremely tight limits, to among other things, comply with the stringent demands with
regard to the hydrocarbon and nitrogen oxide content in the exhaust fumes.
The carburettor needles on these carburettors are fitted with plastic sleeves with
movement limiters, so-called caps.
To carry out adjustment when replacing needles or the entire carburettor the engine
must be under load. This is achieved by fitting a Trimmy Fix with the specified length
and diameter of trimmer cord. Consequently, the stated speed will be much lower
than with “normal” carburettor adjustment 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 fitted when adjusting the H-needle.
Low speed jet L
Find the highest idling speed by slowly turning the low speed
needle clockwise and anticlockwise. When the highest speed
has been found, turn the L-needle 1/4 turn anticlockwise.
High speed jet H
The high-speed H-needle affects the engine’s power and
speed. A too lean H-needle setting (H-needle screwed in too
far) gives too little fuel to the engine resulting in damage to
the engine.
Run the engine at full throttle for about 10 seconds. The H-
needle is set correctly when the engine “splatters” a little.
If the muffler smokes heavily, at the same time as the engine
“splatters” a great deal, the setting is too “rich”. Turn the H-
needle clockwise until you find the setting that sounds right.
When checking the speed on a
trimmer no part of the cord
should be extended.
Use the 502 71 14-01 tachom-
eter to check the speed.
• Carefully screw in (clock-
wise) the L- and H-jets until
they bottom. Now screw out
(anticlockwise) the needles
1 turn. The carburettor now
has the setting H = 1 and
L = 1.
Use special screwdriver 501
60 02-03.
NOTE!
A tachometer should always be used to find the optimal
setting.
The recommended max. speed must not be exceeded.
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.
• Start the engine and run warm for 10 minutes.