Traxxas 4810, Owner'S Manual

The TRX 2.5 Racing Engine

32

See 

Important

Points to Remember

on page 5 for other

precautions.

Never run your
Nitro 4-Tec indoors.
Since the TRX 2.5

racing engine exhaust
fumes are harmful, always
run your Nitro 4-Tec
outdoors, in a well-
ventilated area.

Your TRX 2.5 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 43 for
information on clearing a
flooded engine.

Your carburetor is
pre-set 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.

Breaking-in Your TRX 2.5 Racing Engine

The TRX 2.5 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
Nitro 4-Tec. The break-in time is not the time to impress your
friends with your new Nitro 4-Tec.

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 2.5 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 the TRX 2.5.

We recommend replacing 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.

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.
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.
Keep extra glow plugs handy (Traxxas part #3231). The break-in
process can cause deposits to form on the plug leading to plug
failure.

Follow the instructions exactly for each of the first 6 tanks of fuel.

Starting Your TRX 2.5 Racing Engine for the First Time

Before you start your TRX 2.5 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, keep your Nitro 4-Tec indoors until you’re
ready to start it, then take it outside.

1.

Turn on the radio system according to the instructions 

on pages 18 and 19.

2.

Make sure the throttle is in the idle position.

3.

Connect the EZ-Start controller according to the instructions on

page 31.

4.

Press the starter button 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 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.

If your engine doesn’t start, see 

Troubleshooting Your Nitro 4-Tec

on page 42.

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