Stihl MS 650

84 MS 650, MS 660
Adjust specified engine speeds
within tolerance of +/- 200 rpm.
1. Adjust engine speed with idle
speed screw (LA) to 3,000 rpm.
2. Turn low speed screw (L)
counterclockwise to obtain
maximum engine speed.
If this speed is higher than
3,400 rpm, abort the procedure and
start again with step 1.
3. Use the idle speed screw (LA)
to set engine speed again to
3,000 rpm.
4. Set the engine speed to
2,500 rpm with the low speed
screw (L).
5. Open the throttle wide and set
maximum engine speed to
13,500 rpm with the high speed
screw (H).
If the setting is made too lean there
is a risk of engine damage due to
insufficient lubrication and
overheating.
6. Install new limiter caps.
: Line up limiter cap lug (arrow)
with slot (1) in carburetor.
: Push the limiter caps onto the
adjusting screws until they are
flush with the carburetor body (2).
Limiter caps that have been
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removed once are damaged and
must not be re-used.
Correct operation of the carburetor
is only possible if atmospheric
pressure and internal fuel tank
pressure are equal at all times. This
is ensured by the tank vent.
In the event of trouble with the
carburetor or the fuel supply
system, always check and clean the
tank vent.
Check function by performing
vacuum test on the tank via the fuel
hose.
– Remove the air filter – b 12.1
– Remove the filter base – b 12.1
– Drain the fuel tank.
Dispose of fuel properly in
accordance with environmental
requirements.
: Pull fuel hose (1) off the
carburetor.
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12.6 Tank Vent