Owner's Manual

MS 650, MS 660
English
40
Whenever the low speed screw (L) has
been adjusted, it is usually also
necessary to adjust the idle speed
adjusting screw (LA).
Correcting the carburetor setting for
use at high altitudes
The setting may have to be marginally
corrected if engine performance is
unsatisfactory at high altitudes:
N Check the standard setting
N Let the engine warm up
N Turn the high speed screw (H)
slightly clockwise (leaner) – for
carburetors with H = 3/4 max. up to
the stop
In some countries, the muffler is fitted
with a spark arresting screen.
N If engine performance deteriorates,
check the spark arresting screen in
the muffler
N Let the muffler cool down
Version A
N Remove four screws
N Remove exhaust casing (1) of the
muffler
N Bend back the retaining lugs (2)
N Pull out spark arresting screen (3)
N Clean the dirty spark arresting
screen, replace if damaged or
heavily carbonized
N Refit the spark arresting screen in
reverse order of steps
Version B
In this version, the muffler is equipped
with two spark arresting screens.
N Remove screw (1)
N Lift and pull out the spark arresting
screen (2)
N Clean the dirty spark arresting
screen, replace if damaged or
heavily carbonized
N Refit the spark arresting screen in
reverse order of steps
N Check second spark arresting
screen – as with Version A
If you make the setting too lean it
will increase the risk of engine
damage through lack of
lubrication and overheating.
Spark Arresting Screen in
Muffler
137BA025 KN
1
137BA026 KN
3
2
1
178BA010 KN
2