Club Car 1996 DS Golf Car Gasoline, Service Manual

Page: 242 / 544

Page 14-2
14
G
Main System, Continued:
Trouble in the main system is usually indicated by poor running, or lack of power under heavy load condi-
tions. A dirty or clogged main jet will cause the mixture to become too lean. An overly rich mixture could be
caused by clogging of the air passage or the air holes in the main nozzle, by a loose main jet, or by a loose
main nozzle.
If the engine exhibits symptoms of overly rich or lean carburetion after all maintenance and adjustments are
correctly performed, the main jet can be replaced by a smaller or a larger one. A smaller numbered jet gives
a leaner mixture and a larger numbered jet gives a richer mixture. It is recommended that any change be lim-
ited to one jet size difference from the standard jet.
SLOW SPEED SYSTEM
The slow speed system supplies fuel during low speed running. Low speed running without load requires
very low intake airflow. The throttle valve (2) is almost closed when this is the case, and as high negative
pressure is created on the back side of the throttle valve, intake air is drawn in and metered through the pilot
air jet. The intake air draws fuel, metered by the pilot jet (6), from the carburetor float chamber. The combus-
tible mixture of air and fuel is then delivered into the venturi through the pilot outlet and bypass. When the
engine is operating at low speed, fuel is supplied mainly through the pilot outlet (Figure 14-4, Page 14-4).
The air/fuel mixture is adjusted by the pilot screw (needle valve) (8) (Figure 14-4, Page 14-4).
Standard Jetting
Pilot Air Screw 1 Turn Open
Pilot Jet 45 (x1/100 mm)
Main Jet 80 (x1/100 mm)
Throttle Valve Stop Screw 3/4 Turn Open
Pilot Air Jet 110 (x1/100 mm)
Main Air Jet 160 (x1/100 mm)
CHOKE AND FRESH AIR SYSTEM
The choke system aids in starting the engine in cold weather. When starting a cold engine, the spring loaded
choke cover (1) (Figure 14-4, Page 14-4) is pushed in by hand. This restricts the air flow to the venturi, caus-
ing a very high vacuum that draws fuel into the venturi at a high rate and thus creating a “fuel rich” mixture.
The choke cover is held in until the engine starts, and then is released.
FIGURE 14-1 FIGURE 14-2
FUEL TANK
FLOAT
CHAMBER
MAIN AIR
PASSAGE
CARBURETOR
BORE
MAIN
NOZZLE
MAIN JET BLEED PIPE
ENGINE
AIR CLEANER
AIR FUEL
AIR / FUEL MIXTURE
INTAKE
AIR
CARBURETOR
VENTURI
INTAKE STROKE
OF PISTON