User Manual

The Sportwerks .21 engine features a slide-valve
carburetor and includes three inserts of various
diameters. These carburetor inserts are used to
alter the power curve of the engine. The three
diameters included have the following effect:
6.5mm – Gives smooth controllable
acceleration; offers best fuel
mileage; best-used for slick
tracks/surfaces or beginning
gas drivers.
7.5mm – Develops good mid-range power;
easier to control than the 9mm
insert; best for medium traction,
average-sized tracks/areas.
9mm – Offers explosive, sometimes difficult
to control acceleration; uses the
most fuel; used only for high traction,
large track/open areas; for expert
drivers only.
Setting the needles
While the needles are preset at the factory, it’s a
good idea to verify that the needles are properly
set slightly rich for break-in. Following are the
recommended starting settings:
High-Speed Needle: 3
1
/
2
turns out
(counterclockwise) from closed
Low-Speed Needle: 2 turns out
(counterclockwise) from closed.
Note: When checking the adjustment of the
low-speed needle, it is crucial that the throttle
slide is closed completely and that you do not
over-tighten the needles. When you feel
resistance, immediately stop turning. This is
the closed position.
Starting Your Engine For The First Time
Break-in
The first startups and the first several minutes
that your engine is running is the most
critical time of it’s life and, in many ways, dictates
how well it will perform and how
long it will last.
During the first runs, when the engine starts, the
exhaust should emit blue/white smoke, indicating
that the engine is rich (a good thing during
break-in). During the first tank of fuel, you may
wish to set a higher than normal idle speed in
order to keep the engine from stalling. Drive your
buggy while “blipping” the throttle and avoid
operating the engine at full throttle for more than
2–3 seconds at a time. Run the entire first two
tanks of fuel in this manner. After the first two
tanks of fuel, begin leaning out the high-speed
needle valve 1/8 turn at a time. It generally takes
about 5 or 6 tanks of fuel before you’d want to
start tuning for “maximum” power. Patience
during break-in will be rewarded with an engine
that performs reliably and to its maximum power
potential. Remember, glow plug failure is a
common occurrence when breaking in a new
engine. To test your plug, let the engine idle at a
properly adjusted low-speed needle setting with
the glow igniter attached. Then, remove the
igniter. If you hear no appreciable change in
engine RPM, the plug is still good. If the engine
loads up and the RPM’s decrease, it’s time to
replace the glow plug.
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High-Speed
Needle Valve
Low-Speed
Needle Valve
Idle Screw
Lean
Lean
Carb Insert