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low-Speed Mixture Setting
This screw meters the fuel at low speeds. The low-speed mixture
screw is located in the end of the carburetor, inside the throttle
arm. This screw controls how much fuel enters the engine at idle
and low throttle. This adjustment will smooth the idle and improve
acceleration to mid-speed. Make this adjustment with the throttle
closed, after setting the idle. Gently turn this screw clockwise until
it stops against the needle seat. Be very careful. It's difficult to know
when the needle has seated due to the thread-holding material on
the needle's thread. Overtightening of the screw may result in
damage to the needle seat. Now turn the low-speed mixture screw
counterclockwise 1¾ turns.
Shutting Off the Engine
Before starting the engine, it is important to know how to shut it off.
The correct method is to pinch and hold the carburetor's fuel line at
idle speed, until the engine dies.
Starting the Engine
Before you start your engine for the first time, make sure you have read
all instructions and precautions in this manual. Pay close attention to the
break-in instructions in the next section, and make sure you have read
and understood them before you run your engine.
Your engine must be at room temperature (70°F) or above the first
time you start it. If it's cooler than room temperature outside, remove
all fuel and keep your model indoors until you're ready to start it and
then take it outside. We do not recommend running the model in
temperatures below 35°F.
1. Turn on the radio system.
2. Make sure the throttle trigger on
the transmitter is in the idle (neutral)
position.
3. Connect the EZ-Start controller.
4. Press the starter button in short
two-second bursts and watch for
fuel moving through the fuel line
up to the carburetor. Watch closely!
The fuel moves very fast. If the fuel
doesn't move through the line within 5 seconds, prime the engine
by briefly (one or two seconds) covering the exhaust outlet with
your finger until the fuel is just visible in the carburetor fuel line.
Watch carefully! If the engine is primed too long, it will flood with
fuel and stop turning.
5. Once fuel reaches the carburetor, the engine should quickly
start and idle.
6. Disconnect the EZ-Start controller from the model.
7. Proceed with the engine break-in.
8. Do not rev your engine with no load (wheels off the ground).
• The radio system is not waterproof. Avoid driving through puddles,
wet grass, or mud. Water could damage the electronics.
• Do not continue to operate the Nitro Sport with low batteries.
After the battery power drops below a certain point, the model
will continue with the last command it had from the transmitter.
Indications of low battery power include slow operation and
sluggish servos. On the transmitter, a flashing red light indicates
low transmitter batteries.
• Do not drive the Nitro Sport at night, on public streets, or in large
crowds of people.
Breaking-in the Engine
Once your engine is running, it must be broken-in. The key to
breaking-in your engine is patience. The break-in time will take
about 1 to 1½ hours. During the break-in period, your engine
may appear to malfunction with symptoms such as stalling,
inconsistent performance, and fouled glow plugs. Don't give up
on it! These are just "break-in pains" that every new engine has to
go through. They will disappear once you get through the break-in
period. Just keep it running, and throttle on and off as smoothly as
you can. Sudden bursts or releases of the throttle can
stall your engine. Resist the temptation to tune the engine for
performance and/or run for extended times at wide open throttle.
Soon, after about the fourth tank of fuel, your patience will pay off
with solid, consistent performance.
During Break-in...
• Special break-in fuels are not required.
• Drive the model on a smooth hard surface.
• If possible, avoid running on very hot, humid days.
• Run with the body off for extra engine cooling.
• Turn the mixture screw (needle) clockwise (in) to lean the mixture
and counterclockwise (out) to richen the mixture.
• Do not allow the fuel tank to run completely empty, possibly
leading to a burned plug. An extremely low fuel level causes the
fuel mixture to be too lean.
• Keep extra glow plugs handy. The break-in process, because of the
engine running rich, can cause deposits to form on the glow plug,
leading to failure.
The First Tank of Fuel
Drive the Nitro Sport on a flat, paved surface in an oval configuration. This
will cause you to naturally vary your speed over the entire rpm range.
During this break-in time, ease in and out on the throttle slowly to avoid
stalling the engine. The goal is to simply keep it running. The fuel mixture
setting may require slight adjustment to correct for different altitudes
and temperature. To tell if the engine is running rich (high volume of fuel
flowing through the engine), look for the following conditions:
1. The engine should accelerate sluggishly.
2. There should be a thick trail of blue smoke coming from
the exhaust.
3. If you do not observe the conditions above, then turn the high-
speed needle out 15° (counterclockwise) and retest.
4. Do not rev the engine with the wheels off the ground. High,
no-load rpms can damage the engine, usually resulting in a broken
connecting rod. At the end of the first tank of fuel, stop the engine
and allow it to cool for 5-10 minutes before proceeding.
DRIVING PRECAUTIONS
• If the truck becomes stuck, do not continue to run the engine.
Remove the obstruction before continuing to drive.
• Do not attempt to push or tow objects with the Nitro Sport.
• The model is controlled by radio. It is subject to radio
interference from many sources beyond your control. Since radio
interference can cause momentary loss of control, allow a safety
margin around the truck in order to prevent collisions.
• Use common sense whenever you are driving your model.
Intentionally driving in an abusive and rough manner will only
result in poor performance and broken parts.
(Very Important!)
7
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