39FS 90, FS 90 R
English / USA
: Unscrew and dry off the spark plug.
: Open the throttle wide.
: Crank the engine several times with 
the starter to clear the combustion 
chamber.
: Refit the spark plug. Connect the 
spark plug boot (press it down 
firmly).
: Move the slide control to START.
: Set the choke knob to e –
even if engine is cold.
: Now start the engine.
Throttle cable adjustment
: Check adjustment of throttle cable – 
see "Adjusting the Throttle Cable".
Tank run until dry
: After refueling, press the fuel pump 
bulb at least five times – even if bulb 
is filled with fuel.
: Set choke knob according to engine 
temperature.
: Now start the engine.
Dirty air filters reduce engine power, 
increase fuel consumption and make 
starting more difficult.
If there is a noticeable loss of engine 
power:
: Set the choke knob to g.
: Take out the screw (1) and remove 
the filter cover (2).
: Clean away loose dirt from around 
the filter.
: Grip the filter element (3) at the 
notch (arrow) in the filter housing (4) 
and take it out.
: Fit a new filter element. As a 
temporary measure you can knock it 
out on the palm of your hand or blow 
it out. Do not wash.
: Replace any damaged parts.
: Install filter element in the filter 
housing.
: Refit the filter cover.
: Insert the screw and tighten it down 
firmly.
Exhaust emissions are controlled by the 
design of the fundamental engine 
parameters and components (e.g. 
carburation, ignition, timing and valve or 
port timing) without the addition of any 
major hardware.
Cleaning the Air Filter
1
273BA006 KN
2
4
Motor Management