Sears 502.25502 - Manual (Page 25)

SERVICE AND 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° change in the operation temperature The carburetor
was adjusted at 80° at the factory.
4 The engine is operated above 4 000 feet
If an adjustment is needed, follow the steps below
1 Remove the side panel See "How To Remove The Side
Panels"
2. With your hand, turn the idle mixture screw in a clockwise
direction until you fee! some resistance Turn the main jet
screw in a clockwise direction until you fee! some resistance
CAUTION: Do rsot over tighten the idle mixture screw or
the main jet screw. The carburetor wilt be damaged.
3 Turn the idle mixture screw counterclockwise 1-1/4 turns
Turn the main jet screw counterclockwise 1-5/8 turns
4 Start the erìgine Run the engine for several minutes
5 Move the throttle control to SLOW position
6. Turn the idle mixture screw clockwise until the engine begins
TO loose speed Note the position of the slot in the idle mix­
ture screw
7 Siowly turn the idle mixture screw counterclockwise unti!
the engine runs rough Note the position of the slot In the idle
mixture screw
. 8 Set the idle mixture screw between the two positions in
steps 6 and 7
9 Move the throttle control to FAST position
10 Turn the main jet screw in a clockwise direction until the
engine begins to loose speed (lean mixture) Note the
position of the s!o! in the main jet screw
HOW TO ADJUST THE THROTTLE CONTROL
For the best engine performance, set the throttle control as
follows
Move the throttle contro! to the FAST position
Loosen the ciamp screw so that the cable for the throttle
control СЭЛ move in the cable clamp Do not remove the
cable damp from the control bracket or disconnect the cable
from the engine control lever
Move the engine control lever until the slot in the is aligned
(lines up) with the hole in the control bracket as shown
Tighten the clamp screw. Move the throttle control to the
SLOW position and then back to the FAST position. Check
the alignment of the control lever. See step 3
The throttle control is now set at the correct speed. When the
throttle control is at the FAST position, the engine speed is
3400 ± 100 RPM When the throttle control is in the SLOW
position, the engine speed is 21 50 ± 100 RPM
1 1 Slowly turn the main jet screw in a counterclockwise direc­
tion until the engine runs rough (rich mixture) Note the
position of the slot in the main jet screw
1 2 Set the main jet screw between the two positions in steps 10
and 11
13 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
1 16 turn
1 4 If the engine runs rough when the bladeis) are engaged, the
carburetor mixture is set too rich Turn the main jet screw
clockwise 1/16 turn.
15 Again check the engine by engaging and disengaging the
bladeis) if necessary, repeat steps 1 3 or 14
IMPORTANT; Do not change the engine governor, if the engine
governor needs an adjustment, go to the nearest Sears Service
Center. They have the equipment and experience to make
the adjustment,
F-92533 2 5