Carburetor Adjustments - Bolens QS Series Service Manual

QS, QT
&
1900 SERIES
Page 4-4 REV. 12/78
CARBURETOR ADJUSTMENT
ONAN ENGINE
MODEL 1666 S/N 0100101
THRU 0599999
The carburetor has a main fuel
(high speed) adjustment and an idle
fuel adjustment. The main adjust-
ment affects operation under high
engine speed conditions. Idle adjust-
ment affects operation at idle or low
speed conditions. Under normal
circumstances, factory carburetor
adjustments should not be disturbed.
If the adjustments have been dis-
turbed, turn needles off their seats
1 to 1-1/8 turns to permit starting.
Then, readjust them for smooth oper-
ation. Engine idle speed 1900 RPM.
NOTE:
BAFFLE MUST BE REMOVED
TO ADJUST CARBURETOR.
CAUTION:
FORCING THE NEEDLE AGAINST
ITS SEAT WILL DAMAGE IT. THE
NEEDLE DOES NOT COMPLETELY
SHUT OFF FUEL WHEN TURNED
FULLY IN.
Before final adjustment, allow
the engine to warm up. Make the
idle adjustment under no load. Set
the engine idle speed at 1900 RPM.
Open the main jet until the engine
runs smooth under acceleration with
no load. Slightly more fuel may be
needed (open about 1 /4 turn further)
when sudden load is applied.
Set the throttle stop screw (lo-
cated on carburetor throttle
lever) with no load connected
and while running at a low speed
setting. Turn the screw to give
approximately 1/32 inch (0.8 mm)
clearance between the screw and
pin at idle.
If engine develops a "hunting"
condition (alternate increase and
decrease of engine speed), try
correcting by opening the main
adjusting needle a little more. Do not
open more than 1/2 turn beyond the
FUEL SYSTEM (Continued)
SERVICING
maximum point of power. " .
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