Traxxas 4 Nitro Tec 4810 User manual

OPERATING INSTRUCTIONS
TEC
COVERS MODELS 4804 AND 4810

2
Quick Reference Guide
This guide is a supplement to the operating instructions. It outlines
and simplifies the set-up and running procedure for your Nitro 4-Tec.
This guide is not a substitute however, for the operating
instructions. Read all of your instructions so that you will be fully
informed about the correct use and care of your car.
1. Buy your fuel (Page 3)
• Use Traxxas Top Fuel™. It is a high quality castor/synthetic blended
fuel, available in 10% or 20% nitro blends. It is the only fuel
guaranteed to provide maximum life and top performance from
your TRX engine.
• Do not use fuel with 100% synthetic oil.
• Use the same percentage of nitro during break-in as you plan
to use for normal running. Special break-in fuels are not required.
• Consult with Traxxas (1-888-TRAXXAS) before using other
brands or types of fuel not listed in your Operating Instructions.
2. Install the tires
• See page 6 for instructions on mounting and gluing the tires.
3. Install your batteries
• Install (8) “AA” alkaline batteries into the transmitter. (Page 4)
• Install (4) “AA” alkaline batteries into the 4-cell holder located
under the top plate, at the right front of the car. (Page 5)
• Stretch the ballon provided in your instruction packet over the
batteries to protect them from fuel and corrosion.
• Use new alkaline batteries. Weak batteries will limit the range of
your model and you could lose control of it.
4. Install the antenna (Page 5)
• Insert the black receiver antenna wire through the plastic
antenna tube. Insert the end of the antenna tube into the slotted
post in the chassis (to the left of the fuel tank).
• Fold the remaining antenna wire over the top of the tube and
install the vinyl antenna tip. Do not cut the wire.
5. Connect the EZ-Start battery
• Charge a 7.2V, 6-cell battery pack. Attach
the battery pack to the EZ-Start
control box with the nylon tie
wraps. Plug in the battery
connector to the top of the
EZ-Start control box.
6. Set the carburetor
Your carburetor has been factory preset to the following specs.
Do not readjust your carburetor settings unless you suspect a problem.
• With the throttle closed, set the idle speed by turning the idle
speed screw until there is a 1 to 11/2 mm gap at the widest
part of the opening.
• Close the throttle against the idle stop. Set your low-speed
mixture screw until it is flush with the end of the throttle
barrel.
• Set your high-speed mixture screw to 21/2turns open
(counter-clockwise) from its stop (fully closed), making sure not
to overtighten. Overtightening may cause damage to the needle
seat on the carburetor. 1 turn = 3600, or a complete circle.
7. Put in the fuel (Page 6)
• Use a small fuel bottle or bulb to put fuel into the tank. Only
fill the tank to the bottom of the fill neck. The model can carefully
be refueled while the engine is running.
• Keep your fuel bottle tightly capped.
8. Install the air filter (Page 6)
• Remove the black cap which covers the carburetor air intake.
• Locate the rubber air filter base and install it on the carburetor
intake.
• Insert the pre-lubed foam element into the rubber base.
9. Switch on the radio system (Page 5)
• Always turn the transmitter on first, then turn on the receiver in
the model. Never turn the transmitter off while the engine is running.
When stopping, shut off the engine, turn off the model, and then
turn off the transmitter.
• Extend the chrome transmitter antenna.
• Move the throttle trigger (channel 2) forward and backward to
test the operation of the throttle servo. When the throttle is
pushed forward, the disc brake should engage. Adjust the
throttle trim so that when the trigger is at neutral, the carburetor
is closed against the idle stop.
• Move the steering wheel (channel 1) left and right to test the
operation of the steering. Adjust the steering trim so that the
front wheels are pointing straight ahead.
10. Range test the radio (Page 5)
• With the radio system on, have a friend carry the model the
maximum distance you plan to operate it and test the radio
system’s operation. Do not run the model if the radio is
malfunctioning.
11. Start the engine (Page 7)
• Connect the EZ-Start control box to the connector at the rear of
the car.
• With one hand, hold the throttle half open using the throttle
trigger on the transmitter. With the other hand press the red
button on the EZ-Start. Do not run the starter for more than
5-seconds at a time. Wait 5-seconds between starting attempts.
12. Adjust the running engine (Page 7)
• Re-adjust the idle as necessary. Turn the idle adjustment screw
clockwise to increase the idle speed.
• From idle, slowly advance the engine speed to full throttle. If
the engine dies, slightly lean the high-speed mixture (turning
clockwise, 1/8of a turn maximum) and re-test.
•Never rev the engine full throttle with the wheels off the
ground. Once the engine will accelerate reliably, then the Nitro
4-TEC is ready to drive.
13. Engine break-in (Page 7)
• These are very general guidelines about the break-in procedure.
The break-in section on page seven of your operating
instructions should be read before beginning engine
break-in.
• Never rev the engine with the model’s wheels off of
the ground.
• Set your engine’s fuel mixture as rich as possible during the
first two tanks of fuel.
• Lean the fuel mixture only enough to allow the model to
accelerate without stalling.
• If the car accelerates but sputters or stalls at high speed,
then richen the high-speed mixture 1/8turn (counter-clockwise).
14. After break-in tuning tips
• If the car runs well at high speed, but is slow to accelerate, then
lean the low-speed mixture
• If the car runs well at high speed, but dies when accelerating,
then richen the low-speed mixture.
TEC

WARNING!
THE NITRO 4-TEC IS A HIGH-SPEED, SOPHISTICATED
MACHINE CAPABLE OF REACHING SPEEDS OVER 50MPH.
DO NOT RUN YOUR MODEL AT FULL SPEED UNTIL YOU
HAVE BECOME COMFORTABLE WITH ITS HANDLING AND
CONTROL. SEVERE DAMAGE IS POSSIBLE IN THE EVENT
OF HIGH-SPEED IMPACT. PARTS BREAKAGE DUE TO HIGH
SPEED IMPACTS WILL NOT BE COVERED UNDER WARRANTY.
FOLLOW ALL RECOMMENDATIONS IN THIS AND THE OTHER
ACCOMPANYING MANUALS IN ORDER TO AVOID SERIOUS
DAMAGE TO YOUR MODEL. IF THESE RECOMMENDATIONS
ARE NOT FOLLOWED, THE RESULTING DAMAGE WILL BE
CONSIDERED ABUSE AND/OR NEGLECT, THEREBY
RELEASING BOTH TRAXXAS AND YOUR DEALER FROM
ANY FURTHER RESPONSIBILITY.
INTRODUCTION
Thank you for purchasing the Traxxas Nitro 4-Tec. This man-
ual contains the instructions you will need to operate, and main-
tain your Nitro 4-Tec.Look over the manual and examine the
Nitro 4-Tec carefully before running it. If for some reason you
think the Nitro 4-Tec is not what you wanted, then do not contin-
ue any further. Your hobby dealer absolutely cannot accept a
Nitro 4-Tec for return or exchange after it has been run.
Please read ALL of the Operating Instructions and Precautions
before attempting to drive the Nitro 4-Tec. Even if you are an
experienced R/C enthusiast, continue reading to learn about Nitro
4-TEC’s unique features. Pay special attention to the mechanical
and safety precautions outlined in the manual.
If you have any questions about your new model, feel free to
call Traxxas’ technical support line toll-free at 1-888-TRAXXAS
(1-888-872-9927) Outside the U.S. call 972-265-8000. Technical
support is available Monday through Friday, from 8:30am to 9:00pm
Central time. Technical assistance is also available through
our website at www.Traxxas.com (e-mail us at
[e-mail]). We hope that you will enjoy many hours
of fun with your new Nitro 4-Tec.
FUEL
Fuel is the most critical component for making your engine
perform properly. Improper fuels will cause hard starting, poor
performance, and excessive wear on the engine. For the best
performance from your TRX Pro .15 engine, use
Traxxas Top Fuel™. Traxxas Top Fuel™ is
the only model engine racing fuel which
exceeds all of the Traxxas engine warranty
requirements, is specially formulated to resist
heat, and is guaranteed to provide the best
performance and longest life from your
Traxxas engine. Traxxas cannot guarantee
the quality and consistency of other manufac-
turers’ fuels. If Traxxas Top Fuel™ is not avail-
able from your hobby dealer, the fuels listed
below have been tested by Traxxas and
determined to be satisfactory for use in the
TRX Pro.15.
Dynamite Blue Thunder
Power Master Formula 16
Byron’s Originals Race 1000/2000
Morgan’s Omega (Omega fuel is an airplane
fuel which may be used. The higher oil content however,
will not deliver the same performance and tuning ease as a
good, special-purpose car fuel)
Some fuels are capable of destroying your TRX Pro.15
engine! If you must use a fuel other than those listed, contact
TRAXXAS first, at 1-888-TRAXXAS, to find out if the fuel is safe
for use with TRX engines.
FUEL BOTTLE
Fuel is usually purchased by the gallon or
quart, so a smaller bottle with a dispensing
tube is required to fill the fuel tank. The fuel
tank in the Nitro 4-Tec has a capacity of
75cc. The fuel bottle should always be capped
to prevent the fuel from evaporating and becom-
ing contaminated with debris or moisture. The
alcohol and nitro contents of the fuel will evapo-
rate, thus upsetting the fuel balance and spoiling
the fuel. Do not use old or dirty fuel!
Traxxas #5001-Fuel Bottle
3
PERSONAL SAFETY PRECAUTIONS
Every precaution outlined in this manual needs to be followed
to help ensure safe operation. Operate your model sensibly and
with care and it will be exciting, safe, and fun for you and your
spectators. Failure to operate your model in a safe and responsi-
ble manner could result in property damage and serious injury.
You alone must see to it that the instructions are followed and
the precautions are adhered to.
The Nitro 4-Tec is not intended for use by children with-
out the supervision of a responsible adult. Traxxas
shall not be liable for any loss or damages, whether
direct, indirect, special, incidental, or consequential, arising
from the use, misuse, or abuse of this product and any
chemical or accessory required to operate this product.
•The fuel is dangerous and poisonous. Follow all of the direc-
tions and precautions on the fuel container.
•The fuel can look like a cool drink to a young child. Keep it out
of children’s reach.
•The fuel is flammable. Do not allow sparks, flame, or smoking
in the presence of model fuel.
•The engine emits poisonous carbon monoxide gas. Always run
the model in a well-ventilated area. Never attempt to run the
engine indoors.
•The engine and exhaust become extremely hot during use.
Be careful not to touch these parts, especially when refueling.
•Do not drive the Nitro 4-Tec at night.
•Never, under any circumstances, operate the Nitro 4-Tec
in crowds of people. The Nitro 4-Tec is very fast and
could cause injury if allowed to collide with anyone.
•Because the model is controlled by radio, it is subject
to radio interference from many sources that are beyond your
control. Since radio interference can cause momentary losses
of radio control, always allow a safety margin in all directions
around the model in order to prevent collisions.
•The engine can be very loud. If the noise makes you
uncomfortable, wear ear protection. Be considerate of your
neighbors by not running your model early in the morning or
late in the evening.
• Most importantly, use good, common sense at all times.
Contact Traxxas for assistance: 1-888-TRAXXAS. 972-265-8000 (outside USA). E-mail us at [e-mail]
CAUTION:
FOLLOW ALL PRECAUTIONS PRINTED ON THE CONTAINER
OF FUEL. KEEP IT AWAY FROM FLAMES AND CHILDREN.
THE MIXTURE IS FLAMMABLE AND POISONOUS.

7.2v BATTERY PACK AND CHARGER
The EZ-Start™ electric starter requires a
7.2 volt rechargeable nicad battery pack.
The battery pack straps to the bottom
of the EZ-Start control box with
the supplied tie wraps. The battery
pack must be fully charged in order
to start the engine. It can be
recharged with an overnight “wall
charger”, a peak-detecting charger, or
a 15-minute quick charger. All are available from a hobby dealer.
OTHER REQUIRED EQUIPMENT
To operate the Nitro 4-Tec, you will need these additional items. All
of these items should be available from your hobby shop.
1. “AA” size batteries for your transmitter(8) and receiver(4)
2. Small phillips head and flat screwdrivers (for adjustments)
3. After-run oil (to protect the engine from corrosion)
4. Spare glow plugs (standard plug, Traxxas part #3230; or
heavy-duty plug, Traxxas part #3231).
5. In-line fuel filter (recommended)
6. Spare fuel line (recommended)
7. Hobby quality thin CA glue for the tires
THE TQ RADIO SYSTEM
The Nitro 4-Tec Model 4810 is equipped with the 2-channel TQ
radio system. The following radio system terms will be used
throughout the rest of these operating instructions.
TWO-CHANNEL RADIO SYSTEM - The radio system in your
model consists of the RECEIVER, the TRANSMITTER, and the
SERVOS. It has two channels, one to operate the throttle, and one
to operate the steering.
TRANSMITTER - The TRANSMITTER is the hand-held radio
unit which sends throttle and steering instructions to the model.
RECEIVER - The RECEIVER is the radio unit inside the model
which receives signals from the TRANSMITTER and relays
them to the SERVOS.
SERVO - The SERVOS are the small motor units in the model
which operate the steering, and throttle mechanisms.
FREQUENCY BAND - The FREQUENCY band is the radio
frequency that the transmitter uses to send signals to the model.
All Traxxas RTR models operate on a 27 MHZ FREQUENCY BAND.
CHANNEL - The 27 MHZ FREQUENCY BAND is divided into 6
CHANNELS, so that up to six cars can be operated simultaneously.
These CHANNELS are referred to by their number and flag color.
The chart below lists the channels and their flag colors.
CRYSTAL (X-TAL) - The CRYSTAL is the plug-in device that
determines which channel the RADIO SYSTEM will operate on.
For each CHANNEL, there are two CRYSTALS, one for the
RECEIVER and one for the TRANSMITTER. Of those two
CRYSTALS, the one marked with the lower number (.455 MHZ
lower) must be inserted in the RECEIVER.
CLEARING YOUR FREQUENCY - CLEARING your frequency
means checking to be sure no one else in the area is operating
on the same CHANNEL. You should always do this before operating
your model.
NICAD (Ni-Cd) -These terms stand for rechargeable, nickel
cadmium batteries. These batteries are most economical and
can be recharged up to 500 times.
NEUTRAL POSITION - The NEUTRAL POSITION is the standing
position that the SERVOS seek when the TRANSMITTER controls
are at neutral.
TRIM - TRIM is the fine-tuning adjustment of the NEUTRAL
POSITION of the SERVOS. This adjustment is made by turning the
throttle and steering trim knobs on the face of the TRANSMITTER
4
27MHZ FLAG COLOR CH# TRAXXAS PART#
26.995 BROWN 1 2031
27.045 RED 2 2032
27.095 ORANGE 3 2033
27.145 YELLOW 4 2034
27.195 GREEN 5 2035
27.255 BLUE 6 2036
Antenna
Power Indicator
Steering Trim
Throttle Trim
Throttle Neutral Adjust
Throttle Trigger
Steering Wheel
Power Switch
Servo Reversing Switches
Steering (R), Throttle (L)
Battery
Compartment
CHANNEL 1
STEERING
SERVO
CHANNEL-2
THROTTLE
SERVO
4-CELL
BATTERY HOLDER
PART# 3170
CHANNEL-1
ANTENNA
RECEIVER
ON/OFF
SWITCH
BLACK
NEGATIVE
RED
POSITIVE
CHANNEL-2
BATTERY
WIRE COLORS
BLACK
RED
WHITE
Contact Traxxas for assistance: 1-888-TRAXXAS. 972-265-8000 (outside USA). E-mail us at [e-mail]

5
INSTALLING TRANSMITTER BATTERIES
Install 8 “AA” alkaline batteries into the bottom
of the transmitter as shown in the drawing.
INSTALLING RECEIVER BATTERIES
The receiver battery holder is located underneath the top
plate, just to the right of the fuel tank. Press the tab on the
reusable zip tie to release the battery holder. Install 4 “AA” alkaline
batteries into the battery holder. Alkaline batteries should be used.
Stretch a rubber balloon over the battery holder to prevent fuel
contamination. Install the battery holder into the car and secure it
to the top plate with the reusable zip-tie. Make sure the battery
holder is secure in the model and will not come loose. If the tie
wrap is loose, it will interfere with the middle drive belt.
MOUNTING THE TIRES
The tires in this model are designed for the high-speed
performance of the Nitro 4-Tec. It is very important that
these tires are mounted correctly to the wheels. Failure to
follow these instructions may result in the tire spinning off
the wheel, and could cause severe damage to your vehicle.
1. Before mounting the tires, wash them with hot, soapy water
and dry them thoroughly. Place the foam inserts into the tires.
Stretch and mold the rubber tire around the foam until it is
completely seated in the tire. Remove any waves or wrinkles.
2. It is important to note that the tires have directional treads. The
tread pattern points forward when viewed from the top of the car.
3. Stretch the tire over the wheel rim and seat the tire bead into
the groove in the rim. Make sure that the foam insert is not
pinched between the wheel and the tire.
4. Glue the tires to the rim by pulling the tire back from the rim
and placing a drop of thin CA glue onto the bead. CAUTION:
Wear eye protection to prevent injury from glue spattering
into your eyes. Quickly re-seat the tire bead into the rim and
allow to dry.
5. Repeat step 4 at several points around the tire until it is
secured to the wheel.
6. Allow the CA glue to completely cure before attempting to run
the vehicle. NOTE: The acetone in finger nail polish
remover should dissolve any glue that may come in
contact with your fingers.
RADIO SYSTEM ADJUSTMENTS
• THROTTLE NEUTRAL ADJUST
The throttle neutral adjustment is located on the transmitter
face and controls the forward and reverse travel of the throttle
trigger. There are two settings, 50/50 which allows equal travel
for both forward and brake, and 70/30 which allows more travel
for throttle and less for brake. Change the adjustment by press-
ing the button and sliding it to the desired position. 50/50 is the
recommended setting while running the Nitro 4-Tec.
• SERVO REVERSING SWITCHES
On the front of the transmitter there are two switches. One
for throttle and one for steering. Moving the switches reverses
the direction of the corresponding servos. For example, if you
turn your steering wheel right and the model moves left, then
switch the steering servo reversing switch to correct the servo
direction. You may need to adjust the corresponding trim control
after moving the servo-reversing switch.
TOTAL TRIGGER
MOVEMENT
50%
REVERSE
50%
FORWARD
Contact Traxxas for assistance: 1-888-TRAXXAS. 972-265-8000 (outside USA). E-mail us at [e-mail]

ANTENNA SETUP
Locate the plastic tube and the antenna tip (supplied in the bag with
your instructions). Insert the black antenna wire, extending from the
receiver housing, into one end of the tube and push it all the way
through. Spray the wire with glass cleaner to make it easier to insert.
Insert the tube into the antenna mount in the side of the chassis.
Fold the remaining antenna wire over the top of the antenna tube
and secure it with the vinyl antenna tip.
Under no circumstances should you ever cut your antenna wire.
Its length is specially tuned to the frequency band, and cutting it
could severely shorten the radio’s range. On the transmitter, fully
extend the chrome telescopic antenna.
RADIO SYSTEM OPERATION
Your radio system was pre-adjusted before it left the factory, however,
the adjustment should be checked prior to running the car.
1) Before you ever turn your radio system on, you must “clear”
your frequency. There are six different channels numbered 1
through 6. Each of the six channels is represented by a color.
Look at the crystal in the back of the transmitter to determine
which of the channels your car is operating on. Clearing your
frequency means checking to be sure that no one else in the
area is operating on the same channel.
2) TIP: Always turn the trans-
mitter on first and off last.
This will prevent the model
from receiving stray signals
and running out of control.
Slide the transmitter switch to
the “on” position. A steady
red light should illuminate. A
flashing red light indicates
weak batteries. Weak batteries
will limit the range of the radio signal between your transmitter and
receiver. Loss of the radio signal can cause you to lose control of
the car.
3) Tu rn the car on.
The switch is
located on the
chassis. The ser-
vos should jump
and move to their
idle (neutral) posi-
tions.
4) With the front wheels off the ground, operate the steering control
on the transmitter (channel 1). Check for rapid operation of the
steering servo and that the steering mechanism is not loose or
binding. If the servo operates slowly, check for weak batteries.
Tu rn the “steering trim” control on the transmitter to adjust the
servo so that the front wheels are pointing straight ahead. Check
to be sure that the wheels do not turn more in one direction than
in the other.
5) Operate the throttle trigger on the transmitter to ensure that
the throttle servo
is operating prop-
erly. When the
servo is in the
neutral position,
the carburetor
should be in its
idle position (you
will adjust the
engine idle
speed later).
When the throttle
trigger is pulled all of the way, the carburetor should be in the
fully open position. When the throttle lever is pushed forward,
the brake should be locked and the throttle should not close
any further than when at idle.
RANGE TEST THE RADIO
There are many things such as buildings, power lines, radio
transmitters, etc. which can adversely affect the performance of
your radio system. To make sure you do not have a “runaway”
model, range test the radio system. With the radio system on and
working, hold the car and have a friend carry the transmitter
away from you the distance you plan to run the car. Have the
friend operate the controls on the transmitter to be sure that
everything is working at full range.
PREPARING TO RUN
• INSTALLING THE EZ-START
BATTERY
Use tie wraps to secure
a fully-charged 7.2 volt
battery back to the EZ-
Start control box. Plug the
battery connector into the
face of the control box. The
Contact Traxxas for assistance: 1-888-TRAXXAS. 972-265-8000 (outside USA). E-Mail us at [email protected]
FRONT
0˚ TOE-IN
Wheels pointing straight ahead
6
NEVER TURN THE TRANSMITTER OR RECEIVER OFF
WHILE THE ENGINE IS RUNNING. THE MODEL COULD
RUN OUT OF CONTROL. (The on/off switch only turns
the receiver on and off. It does not turn off the engine.)

7
plug will only go in one way.
STARTING THE ENGINE
STEP 1: INSTALL THE AIR FILTER
Remove the protective cap from
the carburetor air intake. Install the
rubber air filter base and pre-lubed
foam element onto the carburetor
intake. The foam air filter element
may be cleaned and reused.
Always be sure the filter element
is oiled properly before running
the engine. For the best filtration,
use the type of oil made for foam
air filters. It should be available locally from motorcycle shops and
small engine repair shops. Lightweight motor oil or after-run oil
may also be substituted. When the element gets dirty, clean it with
dish soap and rinse. Next, saturate it with oil and then squeeze
out the excess oil. For extremely dusty conditions, special two or
three-stage, pre-lubed filters are available from Traxxas (Part
#4062 and #4063).
STEP 2: FILL THE FUEL TANK
Use a small fuel bottle or bulb to put fuel into the tank. Only fill
the tank to the bottom of the fill neck. The Nitro 4-Tec can be
carefully refueled while the engine is running.
STEP 3: HIGH-SPEED MIXTURE SETTING
The high-speed mixture screw controls how much fuel enters
the engine during mid and high-speed operation. Turn the high-
speed mixture screw clockwise, by hand, until it stops (Do not
tighten or the needle may be damaged). Now, turn the mixture
screw counter-clockwise 2 1/2complete turns.
DRIVING PRECAUTIONS
• 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 4-Tec 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 4-Tec at night, on public streets, or in
large crowds of people.
• If the car 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 4-Tec.
• The model is controlled by radio. It is subject to radio interfer-
ence from many sources beyond your control. Since radio
interference can cause momentary losses of control, allow a
safety margin around the car 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.
Contact Traxxas for assistance: 1-888-TRAXXAS. 972-265-8000 (outside USA). E-mail us at [e-mail]
CAUTION:
TRX ENGINES MUST BE BROKEN-IN FOR MAXIMUM LIFE AND HIGHEST LEVEL OF PERFORMANCE. THIS PROCESS MUST
NOT BE SKIPPED. A SHORTCUT HERE COULD SHORTEN THE ENGINE LIFE.
AIR
FILTER
HIGH SPEED
NEEDLE
Note: Your carburetor has been factory preset
for break-in. Do not readjust your carburetor
settings unless you suspect a problem. The
following steps are for reference only.

STEP 4: SETTING THE IDLE SPEED
The idle screw regulates the throttle opening to control the idle
speed. The throttle opening at idle should be set as shown in the
drawing. The opening should be 1 to 1 1/2millimeters at the widest
point in the opening. The engine may not idle well until it is
warmed.
STEP 5: 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. To get the low speed mixture into the
correct range of adjustment, turn it in or out until the head of the
screw is flush (even) with the end of the throttle arm assembly. This
will be the starting point for future adjustments. Fine tuning the
low speed mixture is described on page 9.
STEP 6: PRIME THE ENGINE
Connect the plug from the EZ-Start control box into the
connector mounted at the rear of the car. The plug is keyed so it
will only insert one way. Closely watch the fuel line going into the
carburetor. Hold your finger over the exhaust outlet and press the
button on the EZ-Start until the fuel moves through the fuel line
towards the carburetor. Once fuel reaches the carburetor, STOP.
If you press the EZ start button too long, you will flood the
engine and the EZ-Start will not be able spin it over (see page
13). With a full tank of fuel, it will only take a second to move the
fuel up to the carburetor.
STEP 7: 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.
STEP 8: START THE ENGINE
Before starting your engine, review the safety and driving
precautions in this manual. (page 3 & page 7)
1) Tu rn the radio system on (transmitter then receiver). Place the
car against a curb or some other immovable object to prevent it
from moving forward.
2) Press the start button on the EZ-Start to turn over the engine.
Do not hold for more than 5-10 seconds to start the engine.
Once the engine has started, it may be necessary to continue
to hold the start button to keep the plug lit until the engine
has warmed up.
Note: The red LED on the EZ-Start will light when the start but-
ton is pressed. This indicates that the glow plug is hot (ignit-
ed). If the LED does not light, make sure that the glow plug
connector (blue wire) is firmly attached to the glow plug. If the
connection is secure, and the LED still does not light, replace
the glow plug with a Traxxas, standard plug #3230.
3) If the engine did not start in step 2, prime it again and retry.
Continue this sequence until the engine starts.
8Contact Traxxas for assistance: 1-888-TRAXXAS. 972-265-8000 (outside USA). E-mail us at [e-mail]
Watch closely
for the fuel to
stop at the inlet

BREAKING-IN THE ENGINE (VERY IMPORTANT!)
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 11/2
hours. During
the break-in peri-
od, your engine
may appear to
malfunction with
symptoms such
as stalling,
inconsistent per-
formance, 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 throt-
tle 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, con-
sistent, performance.
DURING BREAK IN...
•Special break-in fuels
are not required.
•Drive the model on a
smooth hard surface.
•If possible, avoid run-
ning on very hot,
humid days.
•Run with the body off for extra engine cooling.
•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.
•Turn the mixture screw (needle) clockwise (in) to lean the mix-
ture and counter-clockwise (out) to richen the mixture.
THE FIRST TANK OF FUEL
• Drive the Nitro 4-Tec on a flat paved surface in an oval configu-
ration. This will cause you to naturally vary your speed over the
entire RPM range. During this break in time, ease in and out of the
throttle slowly to avoid stalling the engine. The goal is to simply
keep the engine running.
• The fuel mixture setting may require slight adjustment to correct
for different altitudes and temperatures. 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.
• If you do not observe the conditions above, then turn the high
speed needle out 15° (counterclockwise) and retest.
• Do not run at full speed during the first tank of fuel.
• 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.
MAINTENANCE
1) Check the wheels and steering for binding. Check the operation
of the shock absorbers.
2) Check the wiring for any frayed wires or loose connections,
including the wires on the EZ-Start quick connector. Fraying
or melting of the blue wire on your EZ Start system can
cause your glow plugs to immediately short out.
3) Check the tightness of the grub screws in the collars on the
throttle and steering linkages.
4) Check the air filter for proper mounting and filtration.
5) Check the mounting of the receiver and servos.
6) Check the tightness of the wheel nuts with a wrench.
7) Check the fuel tank and all hoses for signs of leaks.
8) Check the operation of the radio system, especially the
condition of the batteries.
9) Check the exhaust system for leaks, cracks, or tears. Do not
run the model if there are any exhaust leaks.
10) Use Traxxas Nitro Wash spray cleaner to keep the model
clean of accumulated dirt and oil. Do not spray any radio
components with Nitro Wash. Do not spray Nitro Wash into
a dirty air filter while it is installed on the engine.
11) The steering servo saver will wear out over time. If the
steering becomes loose, the servo saver should be replaced.
Contact Traxxas for assistance: 1-888-TRAXXAS. 972-265-8000 (outside USA). E-Mail us at [email protected] 9
LEAN
RICH
SAFE RANGE
Optimum
for High-Speed
Performance
Optimum
for Climbing
& Low Speed
Operation
RACING
EVERYDAY
RUNNING
High-Speed Power Loss
Overheating
Sluggish Performance
Break-In Settings
DANGER
2 1/2turns out
2 turns out

10
TANKS TWO-FOUR
Tu rn the high-speed mixture screw clockwise 150and run
through the second tank of fuel. Repeat this process for the third
and fourth tanks of fuel.
Important: Do not lean the high speed mixture less than 2
turns out from closed (see illustration). Also, be sure to
allow the engine to cool between each run.
TANK FIVE AND BEYOND
• All final tuning adjustments must be made to the engine at its
normal operating temperature.
• The engine’s performance depends on the fuel mixture. Leaning
the fuel mixture with the high-speed needle (turning clockwise)
will increase engine power up to engine’s mechanical limits.
Leaning the fuel mixture beyond the safe allowable limits will
result in poor performance and engine damage.
• After the fourth tank of fuel, the break in process should be
complete. Now its time to tune the engine for maximum power.
• Turn the mixture screw in (clockwise) 1/16 of a turn and contin-
ue driving. Note any increase in speed and performance.
• Continue to lean the fuel mixture in 1/16 turn increments until :
1) There is no longer any performance increase or
2) The engine begins to cut out at high speed or
3) The engine begins to overheat. Symptoms include:
• Steam or smoke coming from the engine surfaces
• Hesitation during acceleration (as if running out of fuel)
• Popping or clattering sound when decelerating (detonation)
• The idle speed will fluctuate
• Any of the above symptoms indicate that the fuel mixture is past
the maximum safe lean setting. Turn the mixture screw back out
(counterclockwise) the previous 1/16 of a turn to reach the optimum
fuel mixture setting.
• Turn the mixture screw out another 1/16 of a turn for non-race
applications. This will extend engine component life. This setting
will vary slightly with each engine depending upon fuel brand,
temperature, humidity, etc.
FINE TUNING THE LOW-SPEED MIXTURE
The low-speed mixture screw is located in the end of the throt-
tle shaft (see the drawing on page 7). The low speed mixture
affects the idle quality and the low end engine power and throttle
response. To check your low speed mixture setting, perform this
simple test.
1) Drive the car for several minutes until the engine is in its nor-
mal operating temperature range.
2) Pull it in, stop, and listen to the idle speed. If, after a few seconds,
the idle speed begins to drop then lean the low speed mixture
1/8 of a turn (clockwise) and retest.
3) Continue leaning the engine in small steps until the idle speed
will stay even for at least 20-30 seconds after stopping.
4) The car should accelerate quickly from a standing start without
bogging. The idle should be smooth and consistent. Lean the
mixture 1/8 of a turn (clockwise) and re-test. If you experience
any stalling or hesitation when accelerating, then the low
speed mixture is too lean. Richen it 1/8 of a turn (counter
clockwise) and retest.
SETTING THE IDLE SPEED
Now that the engine mixture is tuned, the idle speed may be
set too high. Only set the idle speed when the engine is at its nor-
mal operating temperature. Adjust the throttle trim on the transmit-
ter so that the brake on the car is
applied. Next, reset the idle speed by
removing the air filter and adjusting
the idle speed screw on the side of
the carburetor (see drawing on page
7). Turn the screw out (counter-
clockwise) to reduce the idle. Re-
adjust the throttle trim on the trans-
mitter as necessary (so that the
brake is no longer applied). The idle
should be set slow enough that the
car does not try to move at idle.
ADJUSTMENTS
• SHIFT POINT ADJUSTMENT
The Nitro 4-Tec comes equipped
with a two-speed transmission. When
the shift point on this transmission
is adjusted correctly, it will maxi-
mize acceleration, improve drivabili-
ty, and minimize lap times. Use a
2.0mm allen wrench to adjust the
shift point.
NOTE: It is important that your
engine is properly tuned and has
Contact Traxxas for assistance: 1-888-TRAXXAS. 972-265-8000 (outside USA). E-mail us at [e-mail]
Positive camber Negative camber
TOE IN
PRE-LOAD
SPACERS
Access hole
Drum

reached full operating temperature before making shift point
adjustments. Stop the engine before making adjustments.
1) Stop engine.
2) Rotate the drum until the access hole is visible from the top.
3) Hold the spur gear set, and roll the car forward while looking
through the access hole. Note that you will see two set screws
through the access hole as you roll the car forward. The first one
holds the two-speed mechanism to the shaft. Do not loosen this
screw unless you want to remove the two-speed mechanism. The
second is the adjustment set screw. Refer to the drawing to
identify the screws.
4) Insert a 2.0 allen wrench through the clutch drum and into
the adjustment set screw. (See diagram)
5) Turn the adjustment screw clockwise to raise the shift point
(later shifts). Be careful not to overtighten the adjustment
screw or you may damage the tension spring.
6) Tu rn the adjustment screw counter-clockwise to lower shift
point (earlier shifts). Be careful not to loosen the adjustment
screw too much or you may cause the screw and spring to fall out.
7) Use 1/8turn increments to find the approximate, desired shift point.
8) Check performance by running a test lap after each adjustment.
9) Use 1/8-1/16 turn increments to fine tune the shift point.
NOTE: The transmission may not shift if the adjustment
screw is turned too far in (locked in first gear), or too far out
(locked in second gear). If the car has quick acceleration
and does not appear to shift, the transmission is never
reaching the shift point. The shift point needs to be lowered
by turning the adjustment screw counter-clockwise. If the
car has poor acceleration but very high top speed, the
transmission is shifting into second gear almost instantly.
The shift point needs to be raised by turning the adjustment
screw clockwise.
• ALIGNMENT SPECS
The Nitro 4-Tec is supplied with soft-compound, race-quality
tires. Due to the high power output of the Pro-15 engine and the
high performance nature of the tires, suspension alignment is
critical to achieving maximum tire life. Proper alignment promotes
even and consistent tire wear as well as predictable and balanced
handling.
• CAMBER
The camber angle of both the front and rear wheels can be
adjusted with the camber rods (upper turnbuckles). Use a square
or right-angle triangle to set the camber accurately. Adjust the
front wheels to 0 degrees of camber (wheel is perpendicular to
the ground). In the rear, adjust the wheels to 1 to 2 degrees of
negative camber. These adjustments should be set with the car
positioned at its normal ride height.
The following information gives recommended stock alignment
settings for the Nitro 4-Tec with stock tires and inserts.
11
Contact Traxxas for assistance: 1-888-TRAXXAS. 972-265-8000 (outside USA). E-mail us at [e-mail]
1) Remove the right, rear wheel.
Remove the E-clip from the two-
speed shaft. Slide the pulley and
belt off of the shaft, being careful
not to lose the pin that sits under
the pulley. Remove the pin. Slide
the spur gears off of the shaft.
NOTE: If you are using optional
gears, you may have to loosen
the right chassis stiffener to
remove the spur gears.
2) Lock the flywheel with a flathead
screwdriver to immobilize it. Use a
2.5mm allen wrench to unscrew the
caphead screw that holds the
clutch bell to the clutch adapter nut.
Remove the clutch bell.
3) To separate the gears from the
clutch bell, gently grip the clutch
bell with channel-lock, adjustable
pliers. Cover the gears with a cloth
to protect the teeth. Using the pliers,
unscrew the gears counter-clockwise.
4) New clutch gears simply screw onto
the clutch bell. Reinstall the clutch
bell and caphead screw onto the
clutch adapter nut. Reinstall the
spur gears, pin, pulley and belt.
Secure them on the two-speed
shaft with the E-clip.
5) To adjust the gear mesh, first
loosen the four 3x10 countersunk
hex screws in the slotted holes in
the bottom of the chassis. Next,
remove the two countersunk Phillips
head screws in the bottom of the
chassis which hold the slotted
engine mount. The engine should
now slide back and forth. Slide a
strip of thin note paper between the
spur gears and the clutch bell
gears. Push the clutch bell gears
against the spur gears and tighten
the screws on the bottom of the
chassis. Remove the paper and the
gear mesh is now correctly adjusted.
GEAR CLUTCH SPUR PRIMARY OVERALL SPEED
TEETH TEETH REDUCTION REDUCTION (EST. MPH)
NITRO 4-TEC STOCK 1st ........16 ........41 ........2.5 ............5.81 ..........37.3
EQUIPMENT 2nd ........20 ........37 ........1.85 .........4.19 ...........51.6
Ratio Characteristics: Moderate acceleration, highest top speed
Recommended Application: Sport/recreational running in very large areas
OPTIONAL CLUTCH GEARS 1st ........15 ........41 ........2.73 .........6.20 ..........34.9
w/STOCK SPUR GEARS 2nd ........19 ........37 ........1.95 .........4.41 ..........49.0
Ratio Characteristics: Good acceleration, very high top speed
Recommended Application: Sport/recreation running in very large areas
STOCK CLUTCH GEARS 1st..........16 ........45 ........2.81 .........6.38 ..........34.0
w/OPTIONAL SPUR GEARS 2nd ........20 ........41 ........2.05 .........4.65 ..........46.6
Ratio Characteristics: Very good acceleration, high top speed
Recommended Application: Sport/recreation, racing on large 1/8 scale size tracks
OPTIONAL CLUTCH GEARS 1st ........15 ........45 ........3.00 .........6.80 .........31.8
w/OPTIONAL SPUR GEARS 2nd ........19 ........41 ........2.16 .........4.89 .........44.3
Ratio Characteristics: Explosive acceleration, moderate top speed
Recommended Application: Racing on small, tight tracks.
Recreational running in small areas.
.25¨ (6mm)
Left side frame Right side frame
Rear of car Rear of car
T
i
g
h
t
e
n
T
i
g
h
t
e
n
Increasing
rear belt
tension

The splines inside the steering servo saver and the throttle
servo arm are compatible with Traxxas and Futaba servos. Other
brands of servos may not fit properly and require you to purchase
a compatible servo saver and servo arm. The designs are an
industry standard so it should not be difficult to locate identical
parts that will fit your servos.
Install the radio system components and hook up the linkages
as shown in the drawings on the right. Route your wires neatly to
prevent them from being damaged.
INSTALLING THE BODY MOUNTS
The body mount parts are located in a separate bag with your
instructions. The front body mount posts attach to the front bumper
with 3x10mm countersunk self-tapping screws. Now slide the foam
bumper over the front mounts, as shown in the drawing. The
excess length of the mounts should be trimmed off after the body
is installed. The rear body mounts attach as shown in the drawing.
12 Contact Traxxas for assistance: 1-888-TRAXXAS. 972-265-8000 (outside USA). E-mail us at [e-mail]
3x14mm Washerhead
Self-tapping screws
3x10mm Countersunk
Self-tapping screws
Installing the front
body mounts
Installing the rear
body mounts
Foam Body Bumper
Front Camber Degrees ..........-1.0
• Rear Camber Degrees ..........-1.0
• Front Caster Degrees* ..........12.0
• Front Toe-In Degrees ..............0.0
* This setting is achieved by having the 1mm caster spacer in the front
and the 2mm caster spacer in the rear (where the upper suspension
arm attaches to the upper suspension arm mount).
• TOE IN
Set the steering trim on your transmitter to neutral. Now, adjust
your tie rods so that both wheels are pointing straight ahead and
are parallel to each other (0 degrees toe in). This will ensure the
same amount of steering in both directions. If you run out of
adjustment, then the steering servo will have to be re-centered
(see “centering your servos on page 11).
• SHOCKS
The four shocks on your Nitro 4-Tec have the most influ-
ence on its handling. Whenever you rebuild your shocks, or
make any changes to the pistons, springs or oil, always do it
carefully and in pairs (front or rear). Piston head selection
depends on the range of oil viscosities that you have available.
For example, using a one-hole piston with a lightweight oil will

• ENGINE COOLING
The windshield should be cut out as shown to allow cooling air
to reach the engine head.
ENGINE & EZ-START ACCESS HOLES
The back of the body must be cut to allow cooling and access
to the engine. The body is scored for the engine access hole. To
the right is a template for positioning of the EZ-Start access hole.
A
l
i
g
n
e
d
g
e
a
t
b
a
s
e
o
f
w
i
n
d
s
h
i
e
l
d
A
l
i
g
n
e
d
g
e
a
t
b
a
s
e
o
f
r
e
a
r
w
i
n
d
o
w
cut out for EZ-Start plug
Front
Rear
These templates have been provided to
locate the holes on the body for the front
and rear body mounts. Cut out the templates
along the solid lines as close to the edge
as possible. Tape the templates to the body.
Use a Dremel™ motor tool or tapered reamer
to make the holes in the body material.
13
Nitro 4-T ecbody mounting hole template
Contact Traxxas for assistance: 1-888-TRAXXAS. 972-265-8000 (outside USA). E-mail us at [e-mail]

15
LIMITED WARRANTY INFORMATION
Every effort has been made in component design and material
selection to make your Nitro 4-Tec as durable as possible.
Because the model is intended to be a hobby-class model and
operate at a much higher level of performance than a “toy,” no war-
ranties can be expressed or implied relating to the longevity of the
parts. Parts will wear out and require replacement. If any part of the
model appears to be defective, or incorrectly assembled when it is
new (before it is used), it will be repaired or replaced at Traxxas’ dis-
cretion.This warranty will not cover damage from wear, abuse, neglect,
crashes, or water.
The radio system that is provided with the ready-to-run models
is covered by separate warranty on a separate page (included in
your documentation package). The radio system warranty does not
cover water damage. Due to the special nature of the TRX Pro.15
engine, it is also covered by a separate warranty page provided with
your model.
Traxxas reserves the right to make changes, modifications
and improvements to this product without notification,
and which may not be reflected in these documents. Upgrades and
improvements are not necessarily retroactive.Traxxas may not pro-
vide improved or updated components free of charge for models
built prior to any change in specification.
• TO OBTAIN WARRANTY SERVICE
If it has been determined that your model is somehow defective,
return it to Traxxas with a note describing the problem, and a copy
of the purchase receipt or invoice. Do not return to Traxxas without
first speaking with a service technician, toll-free, at 1-888-
TRAXXAS. Drain all fuel and remove all batteries. Remember that
the warranty only covers brand new products which are defective
right out of the box. All other service or exceptions will be estimated
on an individual basis.
Be sure to include a return address and a daytime phone number.
MAIL OR SHIP TO:
TRAXXAS
1100 KLEIN RD.
PLANO TEXAS 75074
For technical assistance regarding your model,
call 888-TRAXXAS (872-9927),
972-265-8000 (outside of the U.S.A.),
or e-mail Traxxas at suppor[email protected]
For orders and other information,
call 972-265-8000 or fax [phone].
Contact Traxxas for assistance: 1-888-TRAXXAS. 972-265-8000 (outside USA). E-mail us at [e-mail]
ENGINE TROUBLE SHOOTING
The troubleshooting guide on the following page has been pro-
vided to help you in diagnosing and repairing common engine
problems. Most difficulties with engines can be traced back to
problems with adjustment, fuel quality, dirt blockage, or common
parts that wear with everyday use.
FLOODED ENGINE
The engine can become flooded if it is primed too many times
during the course of a routine start up. When the engine is flooded,
the EZ-Starter cannot turn the engine and it will appear to be
locked. Use the following procedure to clear a flooded engine.
• Remove the blue glow plug wire
• Remove the glow plug with a 5/16 nut driver
• Plug in the EZ Start and turn the car upside down
• Push the EZ-Start button for several seconds to clear the
excess fuel from the combustion chamber
• Turn the car over and re-install the glow plug with gasket
• Reconnect the blue glow plug wire
• Remove one of the motor wires from the EZ-Start motor
• Push the EZ-Start button for several seconds. This lights the
glow plug and burns off any remaining fuel
• Reconnect the EZ-Start motor
• Do not prime the engine. Partially open the throttle and press
the EZ-Start button. The engine should start immediately.
GLOW PLUGS
The glow plug in your engine is a consumable item which
must be replaced periodically to maintain peak performance and
starting ease. To test for a leaking glow plug, place a few drops
of fuel around the the base of the glow plug when the engine is
cool. With the engine running, look for bubbles around the glow
plug. If the gasket is leaking, tighten the plug or replace the gas-
ket.
The EZ-Start control box has an LED which lights to indicate
the condition of the glow plug. If the LED does not light when the
button is pressed, then the glow plug element is broken.
However, glow plug performance can deteriorate significantly
before the element actually burns in two. The only sure way to
test for a faulty glow plug is to replace it with a new one to
see if the problem goes away. You can view the glow plug
element by removing it and touching it against the engine head
while pressing the EZ-Start button. The glow plug will not light
unless it is grounded against the engine. Glow plugs can be
damaged by particles in the combustion chamber or by running
the fuel mixture excessively lean.
Traxxas makes 2 glow plugs. The standard hot plug
(part#3230) is the stock replacement plug for Traxxas engines.
The optional heavy-duty plug (part#3231) will last longer in most
cases however, it is a medium temperature plug so performance
may be reduced slightly. Do not use plugs with idle bars!
CARBURETOR
Dirt is the main enemy to your carburetor. If you notice a sud-
den change in the fuel mixture (lean) and performance of your
model, you may have dirt lodged in the carburetor. To dislodge a
dirt particle in your carburetor try screwing the high and low
speed needles all the way in and then back out to their original
settings. If the engine doesn’t return to normal operation, then try
backing the mixture screws out and prime the engine to force
fuel through the carburetor. Return the mixture screws back to
their original settings. The engine will be flooded at this point so
follow the directions for relieving a flooded engine. If this fails,
then the carburetor will need to be removed and cleaned with
Traxxas Nitro Wash or denatured alcohol. Do not blow on carbu-
retor passages or fuel lines with your mouth. Fuel and solvents
are extremely poisonous. To prevent this from occurring again,
insert a fuel filter in the line between the tank and the carburetor.
EZ-START
The battery to the EZ-Start must be fully charged for the best
performance. If the battery is weak, the EZ-Start may appear to
be spinning the engine fast enough to start however, there is not
enough current to adequately light the glow plug. If the EZ-Start
appears to spin normally, but doesn’t seem to “catch” and spin
the engine adequately, then inspect the one way bearing inside
the starter. If it becomes saturated with castor oil from the engine
fuel, then it will slip on the starter shaft. Clean or replace the one
way bearing. If there is excessive gear noise, then suspect broken
gears inside the EZ-Starter. If the EZ-Start motor spins freely
with no gear noise, then the motor pinion gear may be stripped. If
this occurs, then the EZ-Start motor assembly must be replaced.
The pinion gear is pressed on, and not available separately.

16
1Out of fuel ........................................................ Fill fuel tank
2Fuel level is low ................................................ Refill fuel tank
3Improper or contaminated fuel ........................ Replace fuel
4Excessive nitro in the fuel ................................ Use fuel with a lower nitro content (page 3)
5Incorrect oil content in the fuel ........................ Switch to a recommended brand of fuel (page 3)
6Poor Quality fuel .............................................. Switch to a recommended brand of fuel (page 3)
7Engine not primed ............................................ Prime engine (page 6)
8EZ-Start battery not charged............................ Use a freshly-charged battery (page 4)
9EZ-Start ground wire (yellow) faulty ................ Clean, tighten, or replace ground wire (page 15)
10 EZ-Start Motor wire loose ................................ Check motor connections on the EZ-Start motor
11 One-way starter bearing slipping...................... Remove EZ-Start/ Clean or replace bearing (page 15)
12 EZ-Start gears damaged .................................. Listen for excessive gear noise/ Replace gears/motor.
13 Glow plug wire loose from glow plug................ Crimp the connector on the glow plug wire
14 Glow plug wire damaged.................................. Replace or repair glow plug wire
15 Leaking glow plug gasket ................................ Check glow plug gasket/ tighten glow plug
16 Glow plug fouled or weak ................................ Check for a solid red light when the EZ-start button is
pressed/ No light indicates a completely shorted plug/
Replace with Traxxas 3230 or 3231 glow plugs (page 13)
17 Engine flooded.................................................. Clear the engine of excess fuel (page 13)
18 Engine overheated............................................ Allow engine to cool- find cause for overheating
19 Exhaust blocked .............................................. Clear any obstructions
20 Air cleaner plugged .......................................... Clean and replace air cleaner element (page 7)
21 Carburetor incorrectly adjusted ........................ Readjust carburetor to factory break-in settings (page 7)
22 High-speed fuel mixture is too rich .................. Lean the high-speed mixture (page 7,9)
23 High-speed fuel mixture is too lean.................. Richen the high-speed mixture (page 7,9)
24 Low speed mixture misadjusted ...................... Fine tune the low speed mixture adjustment (page 7,9)
25 Low speed mixture too lean ............................ Richen the low speed mixture adjustment (page 7,9)
26 Low speed mixture too rich .............................. Lean the low speed mixture adjustment (page 7,9)
27 Idle speed set too low ...................................... Increase idle speed (page 9)
28 Fuel flow blocked .............................................. Check that all fuel lines are clear with no pin-hole leaks
Check for dirt blockage in the carburetor fuel inlet and
high-speed needle seat/ Install inline fuel filter (page 13)
29 Air bubble in the fuel line .................................. Prime the engine to force the air through/ Check for pin-
hole leaks in the fuel line
30 Insufficient fuel tank pressure .......................... Replace the pressure hose (between pipe and fuel
tank)/ clear blockage in the tuned pipe hose fitting/
check flow to and from tank/ Check fuel tank cap seal
31 Engine overheated............................................ Allow engine to cool/ find cause for overheating
33 Engine overgeared for application.................... Use a lower gear ratio (page 11)
34 Engine clutch slipping ...................................... Replace clutch shoes (see engine repair section, page 15)
35 Drive system is bound ...................................... Locate the bound item and repair
36 Engine excessively worn .................................. Repair or replace engine (page 15)
37 Cooling air to the head is blocked .................... Cut ventilation holes in the body (windshield)
38 Excessive load on the engine .......................... Check for bound drivetrain
39 Broken clutch shoe spring ................................ Replace clutch shoe spring (page 15)
40 Loose flywheel.................................................. Replace flywheel nut (page 15)
41 EZ-Start motor pinion stripped .......................... Replace EZ-Start motor
Engine will not start 1 3 7 28 8 16 13 14 21 29 19 39 40 36
EZ-Start motor will not turn 8 10 17
EZ-Start turns but engine does not 11 12 41
Engine starts and then stalls 16 21 27 24 29 28 30 36
Engine sluggish, poor performance 3 6 16 15 21 24 26 22 20 34 33 38 35 36
Engine Overheats 3 4 5 6 21 25 23 28 29 37 38 35
Engine chokes/hesitates at speed 1 2 16 21 23 28 29 30 20 31
Engine stalls under hard acceleration 1 2 16 21 24 25 26 27 28 29
Engine stalls around turns 1 2 30
Engine stalls during normal driving 1 2 3 16 28 29 30 21 20 36
ENGINE TROUBLESHOOTING GUIDE
Contact Traxxas for assistance: 1-888-TRAXXAS. 972-265-8000 (outside USA). E-mail us at [e-mail]

17
STEP 7: Remove the 3x23mm roundhead machine screws that fasten the header to the engine. Carefully remove the header to avoid damaging the gasket. To separate the engine from the engine mount, remove the four 3x8mm caphead machine screws.
REBUILDING THE ENGINE STEP 1: Remove the 4mm locknut from the front pipe hanger. Pull the pipe from the rear exhaust header
STEP 2: Remove the yellow ground wire from the EZ-Start.
STEP 3: Unplug the blue wire from the glow plug. Remove the fuel line from the carburetor inlet and from the exhaust header pressure fitting. Disconnect the red and black wires from the EZ-Start motor.
STEP 4: Turn the car on its side. With a 2mm hex driver and a Phillips head screwdriver, remove the 6 engine mount bolts.
STEP 5: Pull the engine from the chassis. Turn the engine so that the flywheel will clear the brake disk and the throttle linkage to the carburetor will release.
STEP 6: Remove EZ-Start from engine by removing the two remaining Phillips head screws.
STEP 9: Changing the piston and sleeve assembly Use a 5/16 inch nut driver to remove the glow plug and copper gasket.
STEP 10: Use a 2.5mm allen wrench to remove the four 3x12mm cap head screws that fasten the cylinder head. Rock the cylinder head gently from side to side to release it from the sleeve. Note the thin aluminum head gaskets. We recommend that you replace these gaskets with
new ones upon reassembly.
STEP 11: Remove the backplate and the starter shaft. Replace the backplate gasket with a new one during assembly.
STEP 12: The piston and sleeve are a matched set. When the piston and sleeve are disassembled, they must be reassembled in the same orientation. Use a hobby knife to scratch a mark to indicate the location of the piston in relation to the pinning of the sleeve.
STEP 8: Removing the carburetor is not necessary to rebuild the engine, unless you intend to replace the internal bearings of the engine. Remove the carburetor by loosening the 3mm locknut and pulling the carburetor straight up.

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STEP 15: Remove the connecting rod and piston through the top of the crankcase.
STEP 16: To remove the connecting rod from the piston, use a sharp-pointed tool to remove the small metal G-clip in the side of the piston. Do not re-use the old G-clip. When installing a new connecting rod, use the sup- plied new G-clip.
STEP 21: Remove the crankshaft by pulling it straight out of the crankcase.
STEP 22: The bearings are press-fit into the crankcase. To remove them, the crankcase must be heated with a heat gun or torch. The crankcase will expand with heat and release the bearings. To avoid the possibility of burns or other damage, do not attempt remove the
bearings. Clean the bearings by flushing them with denatured alcohol and then place one or two drops of after-run oil on the races.
STEP 23: Before installing a new connecting rod, you can increase connecting rod life by polishing the crank- shaft journal. Use 1200 grit sandpaper to remove the surface scratches followed by liquid metal polish to buff the crankshaft journal to a bright, smooth shine. Rinse thoroughly with Traxxas Nitro Wash or dena- tured alcohol. Lube with after-run oil. STEP 24: Use the 1200 grit sandpaper and the liquid metal pol- ish on the wrist pin also. Rinse thoroughly with dena- tured alcohol and lube with after-run oil.
STEP 13: Pull the sleeve straight up and out of the crankcase. If the sleeve will not move, rotate the crankshaft until the sleeve pushes up.
STEP 14: Rotate the crankshaft to bottom dead center. Lightly grab the connecting rod with a pair of needlenose pli- ers and gently pull it off of the crankshaft journal.
STEP 17: Removing the clutch and flywheel It is not necessary to remove the clutch assembly unless you are servicing the clutch, crankshaft, or engine bearings. Use the tip of a small screwdriver to remove the E-clip which holds the clutch bell gear.
STEP 18: Remove the clutch bell gear and the clutch shoes. Note that there are two 5x8mm teflon washers, one on each side of the clutch bell gear. Check the clutch
shoes for excessive wear or cracking around the pin holes. If the clutch shoes are worn to the point that the clutch spring contacts the clutch bell, then the shoes must be replaced.
STEP 19: Grip the flywheel with a pair of pliers (locking pliers work best). Remove the clutch adapter nut with a 10mm deep socket. Hold the engine just above your workbench and tap the fly- wheel from behind with a
non-marring hammer (plastic or wood). Several easy blows may be necessary to release the flywheel and
split beveled cone.
STEP 20: The flywheel and the split-beveled cone should pull smoothly off of the crankshaft.

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STEP 36: Reinstall the carburetor with a new o-ring, header, a NEW glowplug, and engine mount. Use a new header gasket when re-installing the header on the engine. Reinstall the engine in the car in the reverse order of removal. Don’t forget to reconnect the yellow ground- ing wire to the engine mount. The rebuilt engine must now be broken in.
STEP 31: Reinstall the backplate and a new backplate gasket with the 3x8mm caphead machine screws. Tighten the screws in small increments, in a criss-cross pattern until all the screws are tight.
STEP 32: Install the appropriate size ball bearing into one side of the clutch bell gear. The Nitro Stampede comes stock with an 18-tooth clutch bell gear which requires 5x11mm ball bearings.
STEP 33: Turn the gear over and install the other ball bearing.
STEP 34: Install the split-beveled cone onto the crankshaft. Next, install the flywheel. Install the clutch adapter nut with a
10mm deep socket. Grip the flywheel with pliers while tightening the adapter nut.
STEP 35: Install the clutch shoes exactly as shown in the drawing (leading edge engagement). Next, install a 5x8mm teflon washer followed by the clutch bell gear (with bearings installed). Install the remaining 5x8mm teflon washer followed by the E- clip (see step 14).
STEP 25: To assemble the connecting rod and piston, place a
drop of caster oil in the top end of the connecting rod. Insert the wrist pin through the piston and the top of the connecting rod. Secure the wrist pin with the G- clip. Make sure the G-clip fits securely into the groove machined in the piston. Be careful not to scratch the sides of the piston.
STEP 26: Reinstall the crankshaft into the engine and make sure that it spins freely. Insert the connecting rod and piston assembly through the top of the crankcase. The G-clip should face the carburetor. Put a drop of castor or after-run oil in the bottom end of the connecting rod. Use your fingers to gently push the end of the con- necting rod over the crankshaft journal.
STEP 27: Place another drop of oil on the connecting rod bush- ing. Rotate the crankshaft several times to distribute the oil.
STEP 28: Insert the sleeve into the top of the crankcase. Rotate the sleeve so that the notch in the sleeve will line up with the pin in the crankcase. Holding the engine upside down will make it easier for the sleeve to go over the piston. STEP 29: Install new head gaskets on the head. Use one thick and one thin gasket. Reinstall the head using the 3x12mm caphead machine screws. Tighten the screws in small increments, in a criss-cross pattern, until all the screws are tight.
STEP 30: Reinstall the starter shaft. Align the notch in the starter shaft with the crankshaft journal pin (arrow).

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