Craftsman 247.797900 - Manual (Page 13)

SERVICE & ADJUSTMENT
A
WARNING: ALWAYS STOP ENGINE AND
DISCONNECT SPARK PLUG WIRE AND
MOVE IT AWAY FROM SPARK PLUG
BEFORE PERFORMING ANY ADJUST­
MENTS OR REPAIRS.
THROTTLE ADJUSTMENT
To adjust throttle control lever, loosen or tighten wing
nut until throttle control lever moves with some resis­
tance and still remains in desired position when
engine is running. See figure 14.
Throttle
Control
Lever
The carburetor may need re-adjusting if engine lacks
power or does not idle properly. If adjustments are
needed, proceed as follows.
•
Close idle mixture valve (see figure 15) clockwise
() finger tight only. Forcing may cause damage.
Then open 1-1/2 turns counterclockwise ().
• Start engine and allow to warm for five minutes.
• Move throttle control lever to IDLE position.
•
Rotate throttle counterclockwise (i^ ) and hold
against idle speed adjusting screw. Turn idle speed
adjusting screw until engine is running at 1750
RPM.
• Turn idle mixture valve clockwise () (lean mix­
ture) until engine JUST starts to slow. Then turn it
counterclockwise ( ( r i c h mixture) until engine
starts to run unevenly. Set at midpoint between rich
and lean mixture.
• Recheck idle RPM and readjust if necessary.
• Move throttle control lever to FAST position.
Engine should accelerate without hesitation or
sputtering. If it does not, carburetor should be read­
justed, usually to a slightly richer mixture.
FIGURE 14.
CARBURETOR ADJUSTMENT
A
WARNING: IF ANY ADJUSTMENTS ARE
MADE TO THE ENGINE WHILE THE
ENGINE IS RUNNING (E.G. CARBURE­
TOR), KEEP CLEAR OF ALL MOVING
PARTS. BE CAREFUL OF HEATED SUR­
FACES AND MUFFLER.
Minor carburetor adjustment may be required to com­
pensate for differences in fuel, temperature, altitude
or load.
NOTE: A dirty air cleaner will cause engine to run
rough. Be certain air cleaner is clean and attached to
the carburetor before adjusting carburetor. Do not
make unnecessary adjustments. Factory settings are
satisfactory for most applications and conditions.
Never attempt to change maximum engine speed. It is
pre-set at the factory and should be changed only by
a qualified service technician who has the necessary
equipment.
ENGINE SPEED
Your engine speed has been factory set. Do not
attempt to increase engine speed or it may result in
personal injury. If you believe the engine is running
too fast or too slow, take your air sweeper to the
nearest SEARS Service Center for repair and adjust­
ment.
13