Service And Adjustment; How To Adjust The Carburetor; How To Adjust The Throttle Control - Craftsman 502.255070 Owner's Manual

SEFIVaCE ADJUSTMENT
HOW TO ADJUST THE CARBURETOR
The factory settings for the carburetor are for most conditions, if the
engine is operated under the following conditions, you can adjust
the carburetor mixture.
1 The engine has a loss of power or does not run smooth.
2 A change from summer to winter operation.
3. A 40 degree change in the operation temperature._ The carbu-
retor was adjusted at 80 degree at the facto_
4. The engine is operated above 4,000 feet.
if an adjustment is needed, follow the steps below
1. With your hand, turn the idle mixture screw in a clockwise di-
rection until you feel some resistance_ Turn the main jet screw
in a clockwise direction until you feel some resistance
(Figure 52)_
CAUTION: Do not over tighten the idle mixture screw or the
main jet screw. The carburetor will be damaged,
2. Turn the idle mixture screw counterclockwise 1_/4turns. Turn
the main jet screw counterclockwise lS/e turns
3. Start the engine., Run the engine for several minutes.
4_ Move the throttle control to SLOW position.
5. Turn the idle mixture screw clockwise until the engine begins
to loose speed. Note the position of the slot in the idle mixture
screw,
6_ Slowly turn the idle mixture screw counterclockwise unt[] the
engine runs rough_ Note the position of the slot in the idle mix-
ture screw_
7_ Set the idle mixture screw between the two positions in steps
5_ and 6
tl
12,.
8. Move the throttle control to FAST position
9. Turn the main jet screw in a clockwise direction until the en-
gine begins to loose speed (lean mixture). Note the position of
the slot in the main jet scr'ew.
t0,. Slowly turn the main jet screw in a counterclockwise direction
until the engine runs rough (rich mixture). Note the position of
the slot in the main jet screw
Set the main jet screw between the two positions in steps 9..
and 10,.
13_
14,,
To check the adjustment, operate the engine. If the engine
stops when the blade(s) are engaged, the carburetor mixture
is set too lean. Turn the main jet screw counterclockwise t/16
turn,
if the engine runs rough when the blade(s) are engaged, the
carburetor mixture is set too rich, Turn the main jet screw
clockwise 1/16 turn.
Again check the engine by engaging and disengaging the
blade(s), if necessary, repeat steps 12. or 13..
Mixture Screw
Main Jet Screw
Figure 52
HOW TO ADJUST THE THROTTLE CONTROL
For the best engine performance, set the throttle control as follows,
1. Move the throttle control to the FAST position (Figure 53).,
2_
Loosen the clamp screw so that the throttle control cable
can move inthe cable clamp (Figure54),,Do not removethe
cable clamp or disconnect thethrottle control cable from the
engine control lever,
3. Move the engine control lever until the slot in the lever is
aligned (lines up) with the hole in the control bracket as
shown.
4_ Tighten the clamp screw,. Move the throttle control to the
SLOW position and than backto the FASTposition,, Check the
alignmentofthe throttle control lever_See step 3,,
5,
The throttle control is now set at the cort'ect speed. When the
throttle control is at the FAST position, the engine speed is
3400 + or'- t00 RPM When the throttle control is in the
SLOW position, the engine speed is 2150 + or- 100 RPM
IMPORTANT: Do not change the engine governor, tf the engine
governor needs an adjustment, go to the nearest Authorized
Service Center, They have the equipment and experience to
make the adjustment°
/
ThrottleControl
CHOKE
FAST
SLOW
Figure 53
(
Engine Control Lever - FAST position
(Slotin lover alignedwilhhole inbracket}
Throttle Control
Cable
Cable Clamp
Clamp Screw
Control Bracket
Figure 54
F-936o2 36