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INSTRUCTIONS
FOR ADJUSTING THE MODEL "D" SCHEBLER CARBURETOR
PRECAUTIONS TO
TAKE BEFORE BEGINNING ADJUSTMENT:
Connect the carburetor to the intake as close to the motor as possible
and sot hat the gasoline connection is about eight inches below teh bottom
of the gasoline tank. Clean the tank and the gasoline line thoroughly.
Use copper or brass pipe, with a free passage of three-sixteenths inch.
Do not use rubber tubing for gasoline connection. See that the ignition
is properly timed and that the spark plugs are clean and the points have
the proper gap. This precaution is most important becuase proper carburetion
cannot be obtained if the ignition is faulty.
PRELIMINARY ADJUSTMENTS:
After all connections are properly made, see the the air valve seats lightly,
by adjusting the air valve screw (C). Adjust throttle stop screw (E) so
that the throttle is slightly open. This will prevent the motor "dying"
while making adjustments on the carburetor. The needle valve (A) should
be closed by turning it as far as possible to the right, and then open
it by turning it to the left, one complete turn.
LOW SPEED ADJUSTMENT:
Retard the spark and open throttle about one-fourth. Adjust the needle
valve (A). Turning it to the right decreases and turning to the left increases
the supply of fuel. Adjust this needle until the engine runs smoothly
without missing.
HIGH SPEED ADJUSTMENT:
This adjustment should be made with spark advanced about three-quarters
and wide open throttle. If engine back-fires, the mixture is too lean.
Turn the air valve adjusting screw to the right until the engine runs
smoothly. If after two complete turns on the adjusting screw, the mixture
is still lean, turn the needle valve (A) about one-tenth of a turn to
the left. This furnishes a slightly richer mixture at both high and low
speeds. If the engine runs rich at open throttle, turn the adjustment
screw (C) to the left slightly, and the needle valve (A) about one-tenth
of a turn to the right. After these adjustments are made tighten the lock
nut (D) on the adjusting screw (C), and packing nut (B) on the needle
valve (A). The carburetor should require no further attention.
Note: - On account
of sediment and water in fuel, we advise the use of the gasoline strainer.
Special Service Helps
- When you first
start your motor it is very liable to backfire. This is because all
the parts are cold and a readjustment should not be made until the motor
is thoroughly warmed up.
- Flooding is usually
due to dirt under the float valve. Take off the bowl cap and lift the
float valve to flush out the seat. Some times the entire bowl should
be removed carefully and cleaned thoroughly.
- When the float
valve is seated, the top of the cork float should be level and 1/16"
above the top of the spray nozzle on the 1/2, 3/4, and 2-inch sizes
and 1/32-inch on the 1, 1-1/4, and 1-1/2 inch sizes. This will give
the best economy and performance.
- Do not connect
the air intake of the carburetor to the crank case unless a baffle screen
of NO. 50 mesh brass gauze wire s used to prevent a possible backfire
from entering the crank case.
- Danger of fire
is very largely eliminated by placing under the carburetor a receptacle
covered by a fire screen.
- Use all the exhaust
heat possible about the intake pipe or manifold.
- If the carburetor
is not to be used for several months, remove it, clean it thoroughly
and put on it a thin coating of oil or grease.
- The carburetor
should be attached as close to the motor as possible.
When this carburetor
is used on a 2 cycle 2 port motor, a check valve must be used.
note: this instructions
are from Schebler Form 21, date uncertain.
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