Adjustment (Carburetor With Limiter Cap) - Stihl MS 440 Service Manual

Adjusting engine idle speed
– Adjust engine idle speed with the
tachometer. Set the specified
speeds within a tolerance range
of +/- 200 rpm.
1. Set the idle speed screw LA to a
speed of 3,300 rpm.
2. Turn the low speed screw L
clockwise or counterclockwise
until the maximum speed is
obtained.
If this speed is greater than
3,700 rpm, stop adjustment and
restart with step 1.
3. Set the speed to 3,300 rpm again
with the idle speed screw LA.
4. Adjust the low speed screw L
until the speed equals 2,500 rpm.
Starting from the standard setting,
set the maximum speed of
13,500 rpm with the high speed
screw H:
If the setting is made too lean, the
engine may become damaged as a
result of insufficient lubrication and
overheating!
72
12.4.1 Adjustment (carburetor
with limiter cap)
1 2
Standard setting
The limiter cap must not be
removed for the standard setting!
– With this carburetor, it is only
possible to correct the settings of
the high speed screw H (1) and
low speed screw L (2) within fine
limits.
Then proceed as follows:
– Open the high speed screw H
counterclockwise (max. 3/4 turn)
as far as stop.
– Close the low speed screw L
clockwise as far as stop, then
open it one quarter turn
counterclockwise.
Adjusting engine idle speed
– Check air filter and clean or
replace it if necessary.
– Check the spark arresting screen
if installed and clean or replace it
if necessary.
– Check the chain tension.
– Let the engine warm up.
Adjust the idle speed with the
tachometer. Set the specified
speeds within a tolerance range of
+/- 200 rpm.
1. Set the idle speed screw LA to a
speed of 3,300 rpm.
2. Turn the low speed screw L
clockwise or counterclockwise
until the maximum speed is
obtained.
If this speed is greater than
3,700 rpm, stop adjustment and
restart with step 1.
3. Set the speed to 3,300 rpm again
with the idle speed screw LA.
4. Adjust the low speed screw L
until the speed equals 2,500 rpm.
MS 440, MS 440 C