The TRX 2.5 Racing Engine
32
See Important
Points to Remember
on page 5 for
other precautions.
Never run your
S-Maxx indoors. Since
the TRX 2.5 Racing
Engine exhaust fumes are
harmful, always run your
S-Maxx 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
S-Maxx.The break-in time is not the time to impress your friends
with your new S-Maxx. 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 and #3232).
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 S-Maxx indoors until you’re ready
to start it,then take it outside.If it’s colder than 45 degrees, special
considerations should be made. See cold weather break-in on
page 36.We do not recommend running the model in
temperatures below 35 degrees.
1. Turn on the radio system according to the instructions
on page 18.
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, refer to the TRX 2.5 troubleshooting
section at www.Traxxas.com.If you still have problems, contact
T
raxxas Customer Support at 1-888-TRAXXAS.
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