Onan CCK Service Manual

THROTTLE CLOSED
CUTAWAY VIEW
IDLE
RUBBER SEAT
(ON METERING
VALVE)
MIXER BODY
MIXER BODY
L
AIR ENTRY
PASSAGE IS
BLOCKED
MOVING
VENTURI
(AIR VALVE)
- CLOSED
POSITION
THROTTLE
BODY
THROTTLE
(CLOSED)
GAS ENTRY
PASSAGE IS
BLOCKED
AIR VALVE
(METERING)
SPRING
- EXPANDED
POSITION
AIR ENTRY •
PASSAGE IS
OPEN
moving
VENTURI !U
(AIR VALVE) ^
-OPEN
POSITION
THROTTLE
(OPEN)
gas entry
passage is
OPEN
AIR VALVE
(METERING)
SPRING -
COMPRESSED
POSITION
TO INTAKE
MANIFOLD
FIGURE 30. GAS CARBURETOR OPERATION
The idle adjustment/bypass system consists of an
adjustable port for air through the air/fuel passage
wall which bypasses the venturi to thethrottle. At idle,
the flow of air is past the idle adjustment screw into a
port in the mixer body, past an idle cutoff piston inthe
throttle body where it enters the air/fuel passage. The
idle cutoff piston is normally held in a dosed position
by a spring effectively blocking the passage of air
through the idle port at less than 5 inches of vacuum.
At idle, the piston is retracted allowing air to be
metered by the idle adjustment screw. But during
cranking and under heavy loads, the piston blocks the
idle port enriching the fuel/air mixture for quick starts
and acceleration. The idle mixture adjustment screw
is tapped into the air bypass port in the throttle body.
Turning the screw in or out meters the amount of air
entering the port accordingly. Normally, only a very
small opening past the screw is needed.
CARBURETOR ADJUSTMENTS
Gas engines with LPG carburetors maintain low
exhaust emissions (Carbon Monoxide CO, Hydro
Carbons HC, and Carbon Dioxide C02) as long as:
the carburetor is adjusted properly, the engine
remains in good service condition, and high
temperature, low ash crankcase oil is used.
INITIAL START ADJUSTMENTS (Atfactory
or after service or maladjustment)
1. Set main power mixture to position shown in
Figure 31
2. Turn idle screw in fully clockwise.
3. Turn idle screw out 2-1/2 to 3-1/2 turns coun¬
terclockwise.
34

Onan CCK Specifications

General

Cylinders	2
Ignition System	Battery ignition
Fuel Type	Gasoline
Cooling System	Air-cooled
Fuel System	Carburetor
Starter	Electric
Governor	Mechanical
Max RPM	1800 RPM
Engine Type	4-cycle
Bore and Stroke	3.25 x 3.625 inches (82.55 x 92.08 mm)