S&S Cycle TWO THROAT Carburetor (Serial E1190 & Higher) User Manual

Page 9

Stock

Mild

L a r g e

CID

Strokers

Engines

Big Twin

61"-74"

80"-84"

86" & up

Sportster

models

55"-61"

Up to 74"

75" & up

Idle Mixture Screw

2-3 turns

Intermediate Jet

.029-.030

.030-.031

.032-.033

Intermediate Bleed

.040-.052

Main Jet

.046-.054

.048-.056

.052-.060

11. For those involved in an "all-out" drag racing effort

using very large displacement engines, you may
consider:

Raising the float level

To improve air-flow, removing the choke
assembly and plugging the choke shaft holes
in the carb body as well as running without the
air cleaner element. You may also elect to run
the 1" spacer block, Part#16-0295, and do
some porting work to the induction tract to
further improve air flow.

12. In closing, remember that this carburetor has large

venturi compared to the stock unit. This means that
at low RPMs, velocity through the carburetor is
very low and it is more difficult to energize the main
jet, particularly on stock displacement big twin or
Harley-Davidson

Sportster

models. Because of

the design and with the addition of an accelerator
pump. one can generally "whack" the throttle on at
lower RPMs and still pick up the main jet. With our
stock l000cc Sportster, we were able to "whack it
on" at 1200 RPM in low, 1600 RPM in second,
2000 RPM in third and 2500 RPM in high. Below
those RPMs, we either down-shifted or slowly
rolled the throttle on until RPMs were up sufficiently
to pick up the main jet. After getting your particular
engine jetted properly, you will have to experiment
with the throttling characteristics as this will vary
with different motor configurations.

E. Jetting

Tips

Use a fuel filter to insure foreign material does not
enter this carburetor.

The Two-Throat has an adjustable idle mixture
screw, fixed intermediate jets, fixed intermediate air
bleeds and fixed main jets.

The idle mixture screw, Part #11-2354, is located on
the top of the carburetor. Turning the screw clockwise
(in), will lean the mixture. A counterclockwise motion
(out), will richen the mixture.

The intermediate jets, Part #11-7300, are available
in sizes from .028 to .034 in graduations of .001
with .034 being the richest. Normally, .029 to .033
sizes are used.

The intermediate air bleeds, Part #11-7320, are
made in sizes .028, .032, .036, .040, .043, .046,
.052, .055, .059, and .063, with .063 being the
leanest. Normally bleeds in the middle of the scale
will be used.

The main jets, Part #11-7200, are made in
increments of .002 and range in size from .040 to
.060, with .060 being the richest. They can be
changed after removing the bottom bowl plugs.

When changing any jets, be sure to change in pairs,
as each throat or "barrel" has its own set of jets.

Upon warming the engine to normal operating
temperature after making any jetting changes to the
intermediate system always readjust the idle
mixture screw.

Below is a chart with some basic guidelines to follow while
jetting your Two-Throat carburetor.