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Adjusting the Carburetor
General Information
Your carburetor comes from the factory
with a standard setting.
This is the optimum setting under the
barometric pressure and climatic
conditions at the factory.
It ensures your machine will deliver
maximum power, be fuel efficient and
operate reliably.
Retuning may be necessary if there is a
change in barometric pressure (weather,
altitude), temperature or humidity.
Adjustment of the high speed screw
changes the power output and
maximum RPM of the engine when it is
running off load.
If the mixture is made too lean
there is a risk of engine damage
due to insufficient lubrication and
overheating.
MS 381
Standard Setting
(without tachometer)
H
L
:
Shut off the engine.
:
Check the air filter and clean or
replace it if necessary.
:
Carefully screw both adjusting
screws down onto their seats
(clockwise).
:
Open high speed screw (H) one full
turn.
:
Open the low speed screw (L) one
full turn.
If you do not have a tachometer, do
not set the high speed screw any
leaner by turning it beyond the
standard setting.
Fine Tuning
(with tachometer)
:
Check the air filter and clean or
replace it if necessary.
:
Check chain tension.
:
Start the engine and run until it is
warm.
:
Adjust idle speed correctly (chain
must not rotate).
:
Starting from the standard setting,
use the high speed screw (H) to
adjust the maximum engine speed
with a tachometer to 12,500 rpm
(with bar and properly tensioned
chain).
If the mixture is made too lean
there is a risk of engine damage
due to insufficient lubrication and
overheating.
English
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