McCulloch 250 - CARBURETOR ADJUSTMENT; Idle Speed Adjustment Screw; Idle Fuel Adjustment Needle

CARBURETOR ADJUSTMENT
The carburetor of your chain saw was adjusted at the factc~y for
maximum performance under average cutting conditions. If it
becomes necessary to readjust the carburetor, it should be done
only by a McCulloch dealer or other person experienced in carbu-
1'etor operation , If this is not possible, then follOW these instruc-
tions carefully, for careless adjustment can seriously damage
both carburetor and engine.
L Remove the air filter cover and the air filter from the carbu-
retor enclosure,
2. Slowly turn the main and idle fuel adjustment needles (figure 10)
clockwise with a thin screwdriver until the needles seat.
eaedUue
Do not turn the needles beyond the point of slight
resistance. This will result in jamming the needles
into their seats and damage the carburetor beyond
repair.
MAIN FUEL
~---, ADJUSTMENT
NEEDLE
II!J
3, Open (turn counterclockwise) the main and idle fuel adjust-
ment needles one full turn for a preliminary adjustment.
Idle Speed Adjustment Screw
1. Start and run the e ngine until it is thoroughly warmed up,
2. Turn the idl e speed adjustment screw (figure 11) until engine
speed with the trigger released, is just below the point at which the
sprocket and chain stops turning. (The point at which the clutch
disengages. )
Idle Fuel Adjustment Needle
1. Pull the throttle trigger full back and "gun" the engine several
times to check acceleration.
NOTE
If the idle fuel ad justment needle is turned in too far
(clockwise to a iean condition) the engine will falter
and hesitate on acc e leration. If it is turned out too
far (counterclockwise to a rich condition) the engine
will run rough and smoke heavily on acceleration.
20 Adjust the idle fuel adjustm e nt needle (figure 10) to obtain a
smooth, rapid acceleration every time without faltering. Turn
the needle slowly and gradually to the desired position in steps of
above 1/ 16 turn . CheCK acceleration after each step.
3. Reinstall the air filter element and the air filter cover on the
carburetor enclosure.
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