Traxxas 4902, Owner'S Manual, Page: 28 / 48

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T-MAXX 2.5R
See Important Points to
Remember on page 4 for
other precautions.
Never run your T-Maxx 2.5R
indoors. Since the TRX 2.5R
Racing Engine exhaust
fumes are harmful, always
run your model outdoors, in
a well-ventilated area.
Your TRX 2.5R Racing Engine
doesn’t usually require
priming. If you do need to
prime your engine, watch
the fuel line carefully to
avoid flooding your engine.
See page 44 for information
on clearing a flooded engine.
Factory Needle Settings:
Your carburetor is preset at
the factory to give the
correct air-to-fuel ratio and
idle speed for engine break-
in. Do not adjust the
carburetor unless you
observe a poor running
condition that requires
correction (see page 25 for
stock settings).
Higher nitro requires a
richer fuel mixture. When
running 33% fuel, richen
your high speed needle 3/4
turn if previously running
20% nitro and then re-tune
the engine for maximum
performance. See page 22
for more information.
Breaking in Your TRX 2.5R Racing Engine
The TRX 2.5R Racing Engine uses a ringless, aluminum-brass-chrome (ABC)
piston/sleeve construction. This type of engine design relies on a very
precise running fit between the piston and sleeve for cylinder sealing.
Engine break-in is necessary to allow the piston and sleeve to develop
an extremely precise fit and optimum cylinder sealing. Therefore,
proper engine break-in is critical to achieving the fastest, most reliable
engine performance.
Allow yourself about 1 to 1
1
/
2
hours to complete the break-in procedure.
The engine break-in period will take 5 tanks of fuel in a T-Maxx 2.5R. The
break-in time is not the time to impress your friends with your new T-Maxx
2.5R.
You must wait until the engine is fully broken in before attempting
sustained high speed running. Patience and careful attention during
break-in will reward you with the best-performing TRX 2.5R Racing Engine
possible.
During break-in, your engine may appear to malfunction with symptoms
like stalling, inconsistent performance, and fouled glow plugs. These are
simply the normal “break-in pains” engines sometimes go through. They
will disappear once your engine is fully broken in. Many owners report not
experiencing any of these symptoms with TRX Racing Engines.
We
recommend to go ahead and replace the glow plug with a new one
after the engine break in procedure.
Engine Break-in Procedure
The focus during break-in is to vary and limit the engine speed. This will
be accomplished by accelerating and stopping at different rates for the
first 5 tanks of fuel. As the engine begins to break-in, the duration and
intensity of the acceleration will gradually increase.
Sustained high-speed
running is not permitted until the 6th tank of fuel. Perform the initial
break-in on a large, flat, paved surface. T-Maxx 2.5R is very fast and by
tanks 4 and 5 you will need plenty of room for the truck to run in. Apply
all throttle and braking actions gently. Abrupt acceleration or braking
could cause the engine to stall unnecessarily.
Special break-in fuels are not recommended. Use the same fuel you
plan to use everyday.
If possible, avoid breaking-in the engine on extremely hot or cold days
(see page 30).
Pay careful attention to the fuel level. Do not allow the fuel tank to run
completely empty. An extremely low fuel level causes the mixture to
run too lean. This could result in a burned glow plug or extremely high
engine temperatures.
Do not attempt to break in the TRX 2.5R Racing Engine by idling it on a
stand. This will produce poor results.
Keep extra Traxxas glow plugs handy. The break-in process can cause
deposits to form on the plug leading to plug failure.
Change or clean your air filter after break-in.
Follow the instructions exactly for each of the first 5 tanks of fuel.
Starting Your TRX 2.5R Racing Engine for the First Time
Before you start your TRX 2.5R Racing Engine for the first time, make sure
you have read all instructions and precautions in this manual.
Pay close
attention to the tank-by-tank 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 21° C) or above the
first time you start it
. If it’s cooler than room temperature outside, remove
all fuel and keep your T-Maxx 2.5R indoors until you’re ready to start it and
then take it outside. If it’s colder than 45 degrees, special considerations
should be made. See cold weather break-in on page 30. We do not
recommend running the model in temperatures below 35 degrees.
1. Turn on the radio system (see page 16).
2. Make sure the throttle trigger on the
transmitter is in the idle (neutral) position.
3. Connect the EZ-Start controller according to
the instructions on page 27.
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).
If your engine doesn’t start, refer to the troubleshooting tips beginning on
page 43 or go online to www.traxxas.com/support. If your factory fuel
mixture settings have been altered, refer to page 25. If you still have
problems, contact Traxxas Customer Support at 1-888-TRAXXAS or
support@traxxas.com.
The TRX 2.5R Racing Engine