S&S Cycle Super D Gasoline Carburetor - Manual (Page 4)

NOTE: The enrichment pickup tube that is located directly below
the fast idle plunger is pressed into carburetor body and must
not be removed.
Removal of enrichment/fast idle pickup tube from the
carburetor body may alter its hole size in the main body and
cause irreversible damage to carburetor.
COLD START
1. Open fuel supply valve.
2. Pull enrichment device handle up.
3. Turn on ignition.
4.
With throttle closed or just slightly open, press starter
button, cranking for no more than 5 seconds at a time.
If engine fails to start immediately, slowly open
throttle enough to slightly open the butterfly and
crank starter until engine fires.
5. Once the engine starts leave the enrichment device on
until engine has warmed. If you feel it is necessary,
open throttle slightly to keep the engine running.
HOT START
1. Open fuel petcock.
2. Turn on ignition.
3. With throttle closed engage electric starter.
4.
If engine fails to start immediately, open throttle
slightly and continue to engage starter until the
engine fires.
ADJUSTING THE IDLE CIRCUIT
The idle mixture screw regulates the air/fuel mixture at idle
speeds and works in conjunction with the throttle stop/engine
rpm adjustment screw that is located on the throttle arm. Your
Super D carb is delivered with settings that should work for
initial start-up, but will require adjustment and tuning specific
to your motorcycle.
1. Start engine and let it run for a few minutes until it is
at operating temperature.
2. Initially adjust engine rpm to idle to approximately
950-1000 rpm.
3. Turn the idle mixture screw clockwise--to lean the
mixture--until the engine starts to die. Now turn the
screw counterclockwise--richening the mixture--until
the engine starts to die. Keep track of the distance
(number of turns) between the two points and turn it
back to the mid-point.
NOTE: Whenever intermediate jet change is made, idle
mixture screw must be readjusted.
INTERMEDIATE CIRCUIT
The intermediate range is used in most normal riding
conditions, beginning right off idle and going up until 3000-
3500 rpm depending on the gearing in your motorcycle. For
that reason, you must pay close attention to jetting your
intermediate circuit to achieve optimum performance and best
gas mileage. You can access the intermediate jet by removing
the float bowl assembly. Photo 4
The actual intermediate jet size installed in your carburetor is
indicated on a tag attached or labeled on the box. Keep this
information handy for future reference.
1. Run the bike enough for the engine and oil to reach
normal operating temperature.
2. Verify idle mixture settings again.
3. Go on a road test to check carburetion characteristics.
Maintain a steady speed of 30-, 40- and 50-mph. Once you
set your speed, if you feel or hear popping or backfiring in
the aircleaner, the bike is too lean. Correct this by installing
the next larger jet size in the kit.
4. If the bike accelerates sluggishly or you notice black smoke
from the exhaust, the jetting is too rich. Correct this by
installing the next smaller size jet in the kit.
5. Repeat the road test procedure. The smallest intermediate
jet that eliminates the popping and provides the best
throttle response should also provide the best fuel economy.
6. Adjust idle circuit as necessary.
MAIN JET/HIGH SPEED CIRCUIT
The high speed circuit—controlled by the main jet--begins
around 3000-3500 rpm or 55-60 mph and runs to your
motorcycle’s maximum speed. You can access the main jet by
removing the float bowl plug. See Photo 5.
The actual main jet size installed in your carburetor is indicated
on a tag attached or labeled on the box. Keep this information
handy for future reference.
Determining your main jet size is best determined at a drag strip
because maximum miles per hour and rpm are the best indicators
of the actual horsepower your engine is developing. A dyno will
help you get a good baseline, but the drag strip will assure you
the best performance of your racing carburetor.
4
Photo 5
Photo 4
CAUTION