Fuel System; Carburetor - Onan T260G Service Manual

Fuel System
CARBURETOR
Set the adjustment screw about 1/8 turn outward
(rich) from the midpoint of this range. On Nikki
The carburetor mixture screw settings were set for carburetors the idle adjustment is limited to
1/8
maximum efficiency at the factory and should normally turn. Do not go beyond these limits.
not be disturbed. If adjustments seem necessary, first be
sure the ignition system is working properly and
governor sensitivity is properly adjusted.
If adjustment is needed, refer to Figures 1 and 2 and
proceed as follows:
THROTTLE
CAUTION
Forcing the mixture adjustment
screw tight will damage the needle
and seat. Turn in only until light tension can be felt.
1.
Walbro mixture screw settings:
Turn both mixture screws in until lightly seated
(Figure
l),
then back the idle mixture screw out 1/2
turn and the main mixture screw out 1-3/4 turns.
AND LIMITED IDLE MIXTURE
SCREW.
FS-1406-2
NlKKl CARBURETOR WITH SEMI-AUTOMATIC CHOKE
N i k k i limited idle adjustment mixture screw
settings:
The carburetor has a limited idle adjustment range
between stops
1/8 turn. The screw should only
be adjusted within these limits; in to lean the
mixture, out to richen. There is no main mixture
adjustment.
MAIN FUEL
When replacing the idle mixture screw, turn in until
lightly seated, then back screw out 1-1/2 turns.
Replace limiter cap so the tab
is approximately
ADJUSTMENT
centered.
ADJUSTMENT
IDLE FUEL
FS-1002
2. Start the engine and allow it to warm up thoroughly
(at least 10 minutes).
Some equipment manufacturers may require higher
throttle stop speed and governor low speed rpm
settings. Refer to equipment manufacturer's Opera-
tor's Manual for the correct rpm settings. When rpm
settings are not specified by the equipment manu-
facturer use the rpm settings listed in Steps 3 and 5.
3. Move the engine speed control to the slow position.
Back out the low speed screw on the governor so
the throttle stop screw on the carburetor controls
engine speed (Figure 2). Adjust the throttle stop
screw for 1000 rpm idle.
4. Determine the best idle mixture setting by first
turning the idle adjustment screw in until engine
speed drops and then outward until engine speed
drops again. Over a narrow range between these
two settings, engine speed remains at its highest.
WALBRO CARBURETOR
FIGURE
1.
CARBURETOR ADJUSTMENT
5. Readjust the throttle screw for 1000 rpm idle, then
adjust the governor low speed screw for 1100 rpm
idle.
6. Move the engine speed control to the fast position.
Bend the high speed stop on the governor so the
engine runs at the vehicle manufacturer's recom-
mended speed (Figure 2.)
7. Check the main mixture adjustment (Walbro car-
buretors only) by rapidly accelerating the engine
from idle to full speed. The engine should accelerate
evenly and without hesitation. If it does not, turn the
main adjustment screw out in 1/8 turn increments
until the engine accelerates smoothly, but do not
turn it out more than
1/2
turn beyond the original
setting.
7-1