TM 5-4240-501-14&P
CARBURETION
Two Piece Flo-Jet
Press new seat flush with body using screw and old seat
as a driver. See Fig. 91. Use care to insure seat is not
pressed below body surface or improper float to float
valve contact will occur. Install float valve as shown in
Fig. 93.
Fig. 93 - Float Valve Variations
Checking Float Level
With body gasket in place on upper body and float valve
and float installed, the float should be parallel to the body
mounting surface. If not, bend tang on float until they are
parallel. DO NOT PRESS ON FLOAT TO ADJUST. Fig.
94A and 94B.
Fig. 94 - Checking Float Level
Assemble Carburetor
Assemble venturi and venturi gasket to lower body. Be
sure holes in the venturi and venturi gasket are aligned.
Most models do not have a removable venturi. Install
choke parts and welch plug if previously removed. Use a
sealer around the welch plug to prevent entry of dirt.
Stake welch plug at least twice.
Fasten upper and lower bodies together with the
mounting screws. Screw in nozzle with narrow blunt
screw driver #19061 or #19062, being careful that nozzle
tip enters the recess in the upper body. Fig. 95. Tighten
nozzle securely. Screw in needle valve and idle valve
until they just seat. Back off high speed needle valve 1-
1/2 turns. Do not tighten packing nut. Back off idle
needle valve 3/4 turn. These settings are approximately
correct. Final adjustment will be made when engine is
running.
NOTE: All carburetor adjustments must be made with
the air cleaner installed.
Fig. 95 - Assemble Carburetor
Carburetor Adjustment
Start engine and run to warm up. Then place governor
speed control lever in "FAST" position. Turn high speed
needle valve in until engine slows (clockwise - lean
mixture). Then turn it out past smooth operating point
(rich mixture). Now turn high speed needle valve to
midpoint between rich and lean. Next, adjust idle RPM.
Rotate throttle counterclockwise and hold against stop.
Adjust idle speed adjusting screw to obtain 1750 RPM,
aluminum engines; 1200 RPM, cast iron engines.
Holding throttle against idle stop, turn idle valve in (lean)
and out (rich). Set at midpoint between rich and lean.
Recheck idle RPM. Release throttle. If engine will not
accelerate properly, the carburetor should be re-
adjusted, usually to a slightly richer mixture.
Fig. 96 - Adjusting Carburetor
Governed Idle
To adjust for governed idle, refer to Section 4 for specific
model of engine.
Choke-A-Matic
Remote Control Adjustment
On Choke-A-Matic carburetors, the remote control must
be correctly adjusted in order to obtain proper operation
of the choke and stop switch. For adjustment, see
Section 4.
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