Carburetor Adjustments - Ryobi Lawn Hornet RLH1100A MKIII Operator's Manual

t
MAINTENANCE AND REPAIR INSTRUCTIONS (Continued)
CARBURETOR ADJUSTMENT
4. Start the engine and let it run for a minute.
This unit is equipped with a diaphragm-type cahuretor that
has been carefully calibrated at the factory. In most cases,
no further adjustment will be required.
5. Release the throttle trigger and let the engine idle. If
the engine stops, turn the id!e speed screw (Figs. 28
and 29) clockwise 118 turn at a time (as required) until
the engine idles.
The condition of the air filter is important to the operation of
the trimmer. A dirty air filter will restrict the air flow, which
upsets the fuel-air mixture in the cahuretor. The resulting
symptoms are often mistaken for an out-of-adjustment
cahuretor. Therefore, check the condition of t h e air filter
before adjusting the carburetor. Refer to Air Filter
Maintenance.
If the following conditions are experienced, it may be
necessary to adjust the carburetor:
The engine will not idle
The engine hesitates or stalls on acceleration
-
The loss of engine power that is not corrected by
cleaning the air filter and muffler
The engine operates in an erratic or fuel-rich condition
(indicated by excessive exhaust smoke from the
muffler)
NOTE: Careless adjustments can seriously
damage your unit.
Adjusting the Carburetor
1. Clean the air filter if it is dirty. Refer to Air Filter
Maintenance.
2. Make the initial settings with the engine stopped.
These initial settings should allow you to start and
warm up the trimmer before making the final
adjustments.
Initial ldle Speed Setting
a) For Walbro cahuretors: Back the idle speed screw
(Fig. 28
-
page 13) out. counterclockwise until it
does not contact the carburetor throttle lever. Then
turn the screw in, clockwise, until
it
just begins to
move the throttle lever; then continue turning
2
full
turns.
b) For
Zama
cahuretors: Back the idle speed screw
(Fig. 29
-
page 13) out, counterclockwise, until it
does not contact the throttle valve located inside of
the carburetor. This is accomplished by carefully
watching for the movement of the throttle lever to
stop. Then turn the screw in, clockwise, until
it
just
begins to move the throttle lever, then continue
turning 1 1/2 turns.
m
NOTE: Turn the high speed and idle
mixture screws finger-tight.
Forcing the mixture screws with a
screwdriver will damage the screw
tip and the seat in the carburetor
body.
6. Final ldle Speed And Mixture Settings: Adjust the
idle speed and mixture for smothest engine idle.
a.
Turn the idle mixture screw (Figs. 28 and 29)
clockwise until you hear the fastest idle; then
turn the screw counterclockwise 1/8 turn.
b. Squeeze the throttle trigger. If the engine
falters or hesitates as it accelerates, turn the
idle rnixture screw (Figs. 28 and 29) counter-
clockwise 1/16 turn at a time until the engine
accelerates rapidly.
c.
If the idle speed changes significantly
because of steps a and b. readjust the idle
speed screw (refer to Step 2).
m
NOTE: The Bump Head line spool should not
rotate when the engine idles.
7. High Speed Screw Mixture Adjustment:
a. High speed mixture screw adjustment is not
recommended without a precision high speed
tachometer.
b.
The factory presets the high speed mixture screw
at 1-114 turns out from the closed position. Your
unit should perform well at this setting. If additional
adjustment of the high speed mixture is required,
contact your local authorized service dealer.
3. Initial High Speed and ldle Mixture Setting: Turn
both the high and idle rnixture screws clockwise
(Figs. 28 and 29) until they are lightlyseated. Then
turn the screws counterclockwise 1-114 turns.