Adjusting The Carburetor - Stihl MS 650 Instruction Manual

English / USA

Adjusting the Carburetor

General Information
Your carburetor is preset at the factory
with the standard setting.
This setting is designed to provide an
optimum fuel-air mixture under most
operating conditions.
The high speed screw alters the
engine's power output and the maximum
off-load engine speed.
If the setting is too lean there is
a risk of engine damage due to
insufficient lubrication and
overheating.
If the carburetor has to be adjusted from
scratch, first carry out the standard
setting.
44
Standard Setting
Carburetor with
H = 1 and
L = 1
: Shut off the engine.
: Check the air filter and clean or
replace if necessary.
: Check the spark arresting screen* in
the muffler and clean or replace 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.
* see "Guide to Using this Manual"
Carburetor with
3
H = / and
4
1
L = /
4
: Shut off the engine.
: Check the air filter and clean or
replace if necessary.
: Check the spark arresting screen* in
the muffler and clean or replace if
necessary.
: Turn high speed screw (H)
counterclockwise as far as stop (no
3
more than / turn)
4
: Turn the low speed screw (L)
clockwise as far as stop, then turn it
1
back / turn.
4
* see "Guide to Using this Manual"
MS 650, MS 660