7
ENGINE
TUNING GUIDE
HIGH-SPEED NEEDLE
The “high-speed” needle
is sticking up from the
carburetor. This controls
the fuel to air mixture of
the carburetor. The needle
is pre-set for break-in from
the factory at 4-1/2 turns
out from fully closed. Once
the engine is broken-in, the
high-speed needle would
typically run from 4 to 4-1/4
turns out from closed, depending on the weather, humidity and
altitude above sea level. To richen the mixture turn the needle
counterclockwise. To lean it, turn the needle clockwise.
LOW-SPEED NEEDLE
The “low-speed” needle is
located on the side of the
carburetor. It controls the
fuel mixture at low throttle
settings/idle and is preset
from the factory at 12-
1/2 turns from fully closed
while holding the carburetor
open. Low speed needle
adjustment should only be
done after break-in. There
is a simple way of adjusting the low-speed needle correctly
called the “pinch test.” With the engine at idle, pinch the fuel
line and listen to how the engine speeds up or slows down.
If the engine increases its speed for about 2 or 3 seconds
and then loses speed, the needle is set correctly. If the engine
loses RPM quickly, it is set too lean and the low-speed needle
needs to be opened (counterclockwise) to richen the mixture.
Pinch again to check the mixture. If the engine takes longer
than 4 seconds to slow down, lean (clockwise) the low-speed
needle and then pinch again to check the mixture.
IDLE STOP SCREW
The “idle stop” screw is
located on the backside of
the carburetor. This increases
or decreases the idle speed
without changing the fuel
mixture. The barrel should
be approximately 1mm from
fully closed.
IMPORTANT!
To insure long life and good performance from
your engine, you MUST break-in the engine. The break-in
period is critical for long life of the internal parts of the engine.
This should be done over the fi rst 5 tanks of fuel.
RUNNING THE
ENGINE
Before running the engine, read the manual and watch the
assembly and engine tuning video that came with this kit.
STARTING THE ENGINE
IMPORTANT!
Your radio system must
ALWAYS
be turned
on and the transmitter antenna fully extended when running
the engine!
1.
Fill the fuel tank.
2.
Charge the 6-cell battery (not included) for the Kwik-Pit
Super Start. Install the battery into the unit and connect it
to the starter. Press the button on the starter to check that
it is functioning properly.
3.
Attach the glow starter to the glow plug.
4.
With the throttle at idle, start the engine using the Kwik-Pit
Super Start.
Sometimes it is helpful to start the engine at around half
throttle. When the engine starts, immediately return the
throttle to idle.
IMPORTANT! FIXING A FLOODED ENGINE
If the engine is diffi cult to turn over with the Super Start,
especially if it is brand new, loosen the glow plug a half turn
before starting the engine. This allows some compression to
escape, but the engine will still start. Make sure you tighten
the glow plug after the engine starts. If the Super Start is still
having problems turning the engine over, it is fl ooded – there
is too much fuel inside the engine. Remove the glow plug,
then turn the truck upside down and run the Super Start for
5 or 6 seconds. This will clear the engine of fuel, and you will
notice the engine turns over easier. Replace the glow plug
and repeat the starting procedure.
STOPPING THE ENGINE
Pinch the fuel tubing leading to the carburetor until the engine
stops running.
Never place your fi nger over the exhaust to
stop the engine. This could result in serious burns on your
fi nger. It also causes fuel to back up in the engine, making
it harder to start the next time you run your Raze ST.
BARREL 1mm
FROM FULLY
CLOSED
IDLE STOP SCREW
