Duratrax Maximum BX Installation and operating instructions

Warranty
• DuraTrax®will warranty this kit for 90 days after the purchase date from defects in materials or workmanship. DuraTrax
will either repair or replace, at no charge, the incorrectly made part.
• Make sure you save the receipt or invoice you were gi en when you bought your model! It is your proof of purchase
and we must see it before we can honor the warranty.
• To return your Maximum BX for repairs co ered under warranty you should send your buggy to:
Hobby Ser ices
1610 Interstate Dri e
Champaign, Illinois 61822
Attn: Ser ice Department
Phone: [phone]:00 am - 5:00 pm Central Time M-F
E-mail: [email protected]
Before Building:
We want the building and operating of this ehicle to be a success, so BEFORE remo ing any parts from the parts bags
please read this manual thoroughly and watch the included ideo to familiarize yourself with the model. If for any reason
you think this model is not for you, return it to your dealer immediately. PLEASE NOTE: Your hobby dealer cannot accept
a return on any model after assembly has begun.
ASSEMBLY AND OPERATION MANUAL
© Copyright 1999 Printed in USA DTXZ1048 For Kit DTXC0060/DTXD65**
™

Introduction.................................................................................2
Safet Precautions .....................................................................2
Helpful Hints................................................................................2
Stress-Tech™Parts Guarantee...................................................2
Repair Service.............................................................................2
Specification & Description Changes.......................................3
Screw Information ......................................................................3
Required Items for Completion .................................................3
Tools You Will Need....................................................................3
Finishing the RTR Version.........................................................4
Assembl of the Pre-Built Version............................................6
Preparing the Radio System .................................................6
Section 1: Steering Servo Assembl ........................................6
Section 2: Assembling the Radio Tra .....................................7
Section 3: Installing the Throttle Servo....................................9
Section 4: Throttle & Brake Linkages.......................................9
Section 5: Radio Adjustments.................................................10
Section 6: Prepare the Engine.................................................11
Section 7: Finishing .................................................................12
Section 8: Carburetor Settings................................................12
Section 9: Breaking-In the Engine ..........................................13
Section 10: Running the Engine .............................................13
Section 11: Engine Maintenance.............................................14
Section 12: Performance Tuning.............................................14
Section 13: Maintenance Tips .................................................15
Engine Trouble Shooting .........................................................16
Thank you for purchasing the DuraTrax Maximum BX. This
manual contains the instructions you need to build, operate,
and maintain your new nitro R/C buggy. Read o er this
manual thoroughly before building or operating the
Maximum BX.
When the safety precautions are followed, the Maximum BX
will pro ide years of enjoyment. Use care and good sense
at all times when operating this radio controlled buggy.
Failure to use this ehicle in a safe, sensible manner can
result in injury or damage to property. You and you alone
must insure that the instructions are carefully followed and
all safety precautions are obeyed.
• Do not operate the Maximum BX near people. Spectators
should be behind the dri er or at a safe distance away
from the ehicle.
• The engine and exhaust system produces quite a bit of
noise. If you are disturbed by the amount of noise this
buggy produces, wear ear protection such as earplugs.
Do not run this ehicle when or where it can disturb others.
• The engine and exhaust system can become ery hot.
A oid touching any of these parts during use and until
they ha e cooled down.
• Model engine fuel is poisonous. Make sure you read and
follow all of the precautions on the fuel container. Keep
fuel out of the reach of children.
• Model engine fuel is flammable and when ignited has a
flame that is difficult to see. A oid sparks, flames,
smoking, or any other ignition source when fuel is near.
• The engine emits carbon dioxide just like real cars. Do
not operate this model indoors.
• Before turning on the transmitter, make sure that no one
else is on your frequency.
• A oid working o er a deep pile carpet. If you drop a small
part or screw, it will be difficult to find.
• Place a mat or towel o er your work surface. This will
pre ent parts from rolling off and will protect the work
surface.
• A oid running the buggy in cold weather. The plastic and
metal parts can become brittle at low temperatures. In
addition, grease and oil become thick, causing
premature wear and poor performance.
• Test fit all parts before attaching them permanently.
We ha e engineered the Maximum BX to take the rough
and tumble abuse that makes R/C fun. We are so confident
of the quality and durability of the Stress-Tech™plastic parts
that we will replace any Stress-Tech plastic part you break
during the first 6 months you own the buggy. Just send in
the part to us and we will send you a Free replacement.
Please see the Maximum BX parts list for the items co ered
under the Stress-Tech guarantee.
To recei e your free replacement part please send the
following to the Hobby Ser ices address listed on the co er
of this manual:
• The broken part must be included.
• The part number and description of the broken part.
• Dated copy of your in oice or purchase receipt.
• Your name, phone number and shipping address.
Repair ser ice is a ailable anytime.
• After the 90 day warranty, you can still ha e your
Maximum BX repaired for a small charge by the experts
at DuraTrax’s authorized repair facility, Hobby Ser ices,
at the address listed on the co er of this manual.
REPAIR SERVICE
STRESS-TECH™PARTS GUARANTEE
HELPFUL HINTS
SAFETY PRECAUTIONS
INTRODUCTION
TABLE OF CONTENTS
2

To speed up the repair process, please follow the
instructions listed below.
1. Under most circumstances return the ENTIRE system:
buggy and radio. The exception would be sending in a
Stress-Tech part. See the instructions under Stress-Tech
Guarantee.
2. Make sure the transmitter is turned off, all batteries are
remo ed, and fuel is drained from the tank.
3. Send written instructions which include: a list of all items
returned, a THOROUGH explanation of the problem and
the ser ice needed, and your phone number during the
day. If you expect the repair to be co ered under
warranty, be sure to include a proof of date of purchase
(your store receipt or purchase in oice).
4. Also be sure to include your full return address.
All pictures, descriptions, and specifications found in this
instruction manual are subject to change without notice.
DuraTrax maintains no responsibility for inad ertent errors
in this manual.
Do not use too much force when tightening self-tapping
screws into plastic. O ertightening will cause the threads in
the plastic to strip. We recommend that you stop turning a
self-tapping screw when you feel some resistance as the
head of the screw comes in contact with the plastic. A oid
using powered screwdri ers when assembling this kit. They
tend to o ertighten the screws. Do not use thread locking
compound on any self-tapping screws. The thread locking
compound may damage the plastic. IMPORTANT: Use
thread lock on any fastener that is threaded into metal or
fastened with a nut. Vibration from the engine will cause the
screws to loosen if thread locking compound is not used.
The illustration abo e shows how to identify the types of
screws used throughout this instruction manual.
To operate the Maximum BX these items are required:
• Glow plug starter (Hobbico®Hot-Shot™-HCAR2505)
• Fuel bottle (DuraTrax Kwik-Pit™Bottle - DTXP0125)
• Fuel (DuraTrax Red Alert™fuel - DTXP0520)
• Air filter oil
• Tie straps
• Hobby knife with #11 blade (HCAR0105)
• Glow plug wrench (DTXR1170)
• It is also helpful to ha e a couple of extra glow plugs
on hand. We recommend the O.S®. #A3 plug (OSMG2690)
All of these items are available in a Nitro Starter Pack
from DuraTrax - DTXP0200).
For the Pre-Built version of the Maximum BX, ou will also
need:
• 2-channel radio with (2) standard ser os.
• (12) “AA” batteries - (4) for the recei er and (8) for the
transmitter.
• Small bottle of thread locking compound (GPMR6060).
To assemble the Pre-Built ersion (DTXC0055), you will
need the following tools:
• Phillips head screwdri er
• Flat blade screwdri er
• Needle-nose pliers
• Wire cutters
• Hobby knife (HCAR0105), #11 blades (HCAR0211)
TOOLS YOU WILL NEED
REQUIRED ITEMS FOR COMPLETION
3mm
14mm
M3x14 Screw
3mm
14mm
M3x14
Self-Tapping
Screw
SCREW INFORMATION
SPECIFICATION & DESCRIPTION CHANGES
3

❏Step 1. Remo e the transmitter and buggy from the box.
❏Step 2. Remo e the twist-tie from the recei er
antenna. (The recei er antenna looks like a bundled
thin wire that is attached to the recei er.) Thread the
recei er antenna underneath and through the hole in
the radio plate next to the recei er switch.
❏Step 3. Remo e the antenna tube from the parts
bag. Thread the recei er antenna through the antenna
tube. The antenna will be longer than the antenna
tube. DO NOT COIL OR CUT THE ANTENNA. Press
fit the antenna tube through the hole in the radio plate.
Use a small piece of tape to secure the end of the
recei er antenna to the antenna tube. TIP: Run the
antenna through your fingers to straighten out kinks
before running through the antenna tube.
❏Step 4. Remo e the air filter and tie strap from the
parts bag. Thoroughly soak the air filter foam with
some oil (not
included) and then squeeze out the excess
oil. A light
machine oil (like 3-IN-ONE™) will work well.
Special oils made for air filters are also a ailable in
most hobby and motorcycle shops. Place the air filter
onto the carburetor and secure it in place with the tie
strap. Cut off the excess part of the strap.
❏Step 5. Remo e the four screws from the top of the
radio plate and remo e the recei er battery holder.
❏Step 6. Place 4 “AA” batteries into the battery holder.
Pay attention to the polarity on the batteries. The
bottom (negati e) of the batteries should connect with
the springs in the battery holders.
❏Step 7. Re-install the recei er battery holder under
the radio plate. Make sure that the recei er switch is in
the off position. Plug the connector on the recei er
4
FINISHING THE RTR VERSION

battery into the socket on the recei er switch. Tuck the
wires between the ser o and recei er battery so they
will not get caught on anything.
❏Step 8. Remo e the transmitter antenna from the
holder and screw it into the hole on top of the
transmitter.
❏Step 9. Slide open the battery door on the bottom of
the transmitter and remo e the transmitter battery
holder.
Place 8 “AA” batteries into the holder in the
configuration molded into the plastic on the battery
holder. Re-install the transmitter battery holder into the
transmitter and re-install the battery door.
❏Step 10. Turn on the transmitter using the switch on
the back (see the photo with Step 8), The green light
on the side of the transmitter should light up. If there is
no light on, turn the transmitter off and check to ensure
that the battery holder is making contact with the
copper contacts on the inside of the battery
compartment. Make sure the batteries are installed
correctly. Turn the transmitter on and check for the
green indicator light. If the green light appears, turn off
the transmitter.
❏Step 11. Remo e the plastic from the outside of the
body. Apply the decals if desired.
❏Step 12. Remo e the body clips from the parts bag.
Place the body on the body mounts. On
each body
mount place a body clip.
Congratulations, you ha e completed preparations!
Before running your new buggy, please take the time to
carefully read the instructions and watch the ideo before
running and breaking-in the engine. Make sure you follow
the safety precautions and most of all...HAVE FUN!
5

6
1. Install the batteries in the transmitter and
the recei er battery holders.
2. Extend the transmitter antenna.
3. Connect the steering ser o, throttle ser o
and recei er battery to the recei er.
4. Extend the recei er antenna.
5. Adjust the ser o trims of the transmitter to
the neutral position.
6. Switch on the transmitter.
7. Switch on the recei er.
8. Operate the steering and throttle control.
Make sure the ser o arms mo e in
proportion to the mo ement of the
steering wheel and throttle trigger.
9. Switch off the recei er, then the transmitter.
Before installing the radio s stem in the
pre-built DuraTrax Maximum BX, read the
manufacturer’s instructions manual and
follow the instructions shown below.
Ser o Arm
Steering
Ser o
Throttle Ser o
Recei er Battery Holder
4-AA Batteries
Transmitter
5
6
1Antenna 4
8-AA Batteries
1
Recei er
3
Recei er
Switch
7
Antenna
2
8
PREPARING THE RADIO SYSTEM
ASSEMBLY OF THE PRE-BUILT VERSION (DTXC0060)
Place a check mark in the check boxes after each step is
completed.
❏Step 1. From bags PA001 and PA003, remo e (8) 3 x 8mm
self-tapping screws, and the (2) L-shaped ser o mounts.
❏Step 2. Attach the ser o mounts to the steering ser o
with (4) 3 x 8mm self-tapping screws. Note that the ser o
spline will mount towards the rear of the buggy.
❏Step 3. Attach the steering ser o assembly to the chassis
with (4) 3 x 8mm self-tapping screws in the holes pro ided
as shown abo e.
SECTION 1: STEERING SERVO ASSEMBLY

❏Step 4. From bag PA001, remo e the steering rod. Note
the shape of the rod.
❏Step 5. Use a 3 or 4 hole ser o arm from your radio
system. A 1, 2, or 4-armed ser o arm will work. Cut off all
but one of the arms by scoring both sides of the ser o arm
with a hobby knife and using pliers to snap off the arm.
❏Step 6. Put the steering rod into the third hole from the
center of the ser o arm (approximately 5/8" or 16mm). You
may need to enlarge the hole in the ser o arm with a 5/64"
(2mm) drill or a hobby knife.
❏Step 7. Place the rod connector through the top of the
middle hole in the steering arm. Place a small amount of
thread locking compound onto the threads of the rod
connector. Install the 2mm nut onto the bottom of the rod
connector. Install a 2mm set screw into the top of the rod
connector. Note: When installing the set screw, make sure
not to thread it in too far because the steering rod must pass
through the hole on the side of the rod connector.
❏Step 8. Slip the steering rod through the hole in the rod
connector that is already installed on the ser o sa er. (Use
the screw that came with your radio system to attach the
ser o arm to the steering ser o.) Do not tighten the set
screw on the rod connector. You will make the steering
adjustments later.
❏Step 1. From bag PA002, remo e all of the parts
included; the radio tray, the (2) radio tray mounts, and the
(8) 3 x 8mm self-tapping screws.
❏Step 2. Using the pro ided double-sided tape, attach the
radio recei er to the top of the radio tray. To find the top of
the radio tray, place the large circular hole to the lower left
as shown. Make sure that the recei er is installed in the
space between the sets of screw holes as shown abo e.
SECTION 2: ASSEMBLING THE RADIO TRAY
7

❏Step 3. Attach the switch from your radio system so it is
abo e the top of the radio plate (make sure the switch is in
the OFF position). Remo e the two screws on the top of the
switch. Place the switch plate on top of the radio tray, the
switch body on the bottom of the radio tray and then reinsert
the screws from the top.
❏Step 4. Place foam tape on the bottom of the radio plate.
This will secure the recei er battery into place when the
radio plate is installed.
❏Step 5. Attach the radio tray mounts as shown to the
chassis with (4) 3 x 8mm self-tapping screws.
❏Step 6. Remo e from your radio system the 4-cell recei er
battery holder and install (4) “AA” batteries. The negati e
sides of the batteries are placed against the springs in the
battery holder. Plug the connector on the recei er battery
holder into the connector on the switch. Make sure the switch
is in the OFF position. Place the recei er battery holder
between the radio plate posts.
❏Step 7. Plug the steering ser o, throttle ser o, and switch
into the recei er. See your radio instructions to determine
which channel is steering and which channel is throttle. The
recei er switch plugs into the socket labeled “Battery,”
“Batt,” or “B.”
❏Step 8. Attach the radio tray to the radio posts with (4)
3 x 8mm self-tapping screws.
8

❏Step 9. Fit the antenna tube through the radio tray and
press fit the antenna tube into the radio tray post. Thread
the recei er antenna through the antenna tube. The
recei er antenna wire will be longer than the antenna tube.
DO NOT CUT OR COIL THE ANTENNA. Use tape or cut
1/4" long pieces of fuel tubing to attach the lefto er antenna
wire to the outside of the antenna tube. Use a hobby knife or
drill to cut a hole in the body to route the antenna tube
through.
❏Step 1. From bags PA001 and PA003, remo e the (2) throttle
ser o mounts and (8) 3 x 8mm self-tapping screws.
❏Step 2. Use the (4) 3 x 8mm self-tapping screws to attach
the throttle ser o to the throttle ser o mounts.
❏Step 3. Use the (4) 3 x 8mm self-tapping screws to attach
the throttle ser o and the mounts to the chassis. Make sure
that the ser o spline will be towards the rear.
❏Step 1. From bags PA001 and PA003, remo e the brake
rod, the throttle rod, the brake spring, (3) 3 x 3mm set
screws, the 2mm nut, the rod connector, and (3) 2mm
collars.
❏Step 2. From your radio system remo e a large, X-shaped
ser o arm. Remo e two of the ser o arms as shown. Install
the rod connector in the last hole on the arm as shown in the
diagram abo e (approximately 3/4" or 18mm). You will need
to enlarge the hole with a hobby knife or a 5/64" (2mm) drill
to fit the rod connector. Apply a small amount of thread
locking compound (not included), on the nut to hold it in
place. Secure the rod connector to the ser o arm with the
2mm nut. Do not tighten the nut completely. The rod
connector should swi el easily.
Rod Connector
3/4"
(18mm)
Rod Connector
SECTION 4: THROTTLE & BRAKE LINKAGES
SECTION 3: INSTALLING THE THROTTLE SERVO
9

❏Step 3. Insert the brake rod as shown in the photo. Insert
the brake rod into the ser o arm from the bottom, into the
second hole from the outside of the arm (approximately 5/8"
or 16mm from the center).
❏Step 4. Place the ser o arm on the throttle ser o as
shown in the photo abo e and place the brake rod through
the brake le er. Do not install the ser o arm screw yet. You
will need to make adjustments before running your buggy.
❏Step 5. Insert the throttle rod into the outer hole in the
carburetor arm. Assemble in order, a 2mm collar and the
throttle spring. Next insert the throttle rod through the rod
connector on the throttle ser o.
❏Step 6. Install a 2mm collar at the end of the brake rod
and another 2mm collar at the end of the throttle rod. Place
a small amount of thread locking compound on two of the
(3) 3 x 3mm set screws and thread them into the 2mm
collars. Do not tighten the set screws all the way. In the next
section we will make adjustments to the collars.
• Turn on the transmitter first, then the recei er.
• Center the trims of the throttle and steering channels (see
your radio system manual for the location of the trim
adjustments).
Steering Linkage Set Up
A) Remo e the arm from the steering ser o and re-install
the arm facing straight up (see photo abo e).
B) Position the front wheels so they are aimed “straight
ahead” (note that the tires are aligned slightly inward – this
is called toe-in).
C) When the wheels are straight, tighten the set screw on
the rod connector. Attach the ser o arm with the ser o arm
screw from your radio system.
Throttle Linkage Set Up
A) With the radio system still on, set the throttle in the
neutral position.
B) Remo e the ser o arm from the throttle and replace the
arm so that it is aligned with the centerline of the throttle
ser o case.
C) The brake le er should be perpendicular (i.e. straight) to
the centerline of the chassis as shown abo e.
D) Tighten the 2mm collar on the brake rod so that it is 3/32"
(2mm) away from the brake le er.
SECTION 5: RADIO ADJUSTMENTS
10

E) Push the throttle rod with your finger until the carb closes
as far as possible (the carb will not close completely which
is normal).
F) Tighten the set screw on the outer collar and cut the
throttle rod flush with the outer 2mm collar.
G) Mo e the throttle spring next to the rod connector.
H) Tighten the inner 2mm collar next to the throttle spring
without compressing the spring.
I) Attach the throttle ser o arm with the screw included with
your radio system.
❏Step 1. Remo e the fuel tank by taking out the two
screws on the bottom of the chassis.
❏Step 2. From bag P001, remo e the fuel line, air cleaner,
and tie-strap.
❏Step 3. Cut the fuel line in half. Route one of the lines
from the nipple on the top of the muffler to the top of the fuel
tank. Route the other fuel line from the nipple on the
carburetor to the bottom of the fuel tank. Ensure that the fuel
line is not kinked anywhere along the line. You may ha e to
shorten the line to eliminate kinks.
❏Step 4. Re-install the fuel tank.
❏Step 5. Remo e the air filter and tie strap from the
parts bag. Thoroughly soak the air filter foam with
some oil (not
included) and then squeeze out the excess
oil. A light
machine oil (like 3-IN-ONE) will work well.
Special oils made for air filters are also a ailable in
most hobby and motorcycle shops. Place the air filter
onto the carburetor and secure it in place with the tie
strap. Cut off the excess part of the strap.
SECTION 6: PREPARE THE ENGINE
11

❏Step 1. Bundle all of the wires around the recei er
together with a tie-strap or a twist-tie (not included in the kit).
❏Step 2. Remo e the clear co ering from the outside of
the body.
❏Step 3. Apply decals to the body if desired. For decal
placement, see the photos on the box top.
❏Step 4. Mount the body on the body posts and secure the
body to the buggy with (2) body clips.
Congratulations, you ha e completed assembly! Before
running your new buggy, please take the time to carefully
read the instructions and watch the ideo before running
and breaking-in the engine. Make sure you follow the safety
precautions and most of all...HAVE FUN!
The High-Speed Needle
The “high-speed” needle is sticking up from the side of the
carb. It is located in the brass housing, just abo e the fuel
inlet. It controls the fuel to air mixture of the carb. The
needle is pre-set for break-in from the factory at 1-3/4 turns
out from the fully closed position of the carb. Once the
engine is broken-in, the high-speed needle would typically
run from 3/4 to 1-1/4 turns out from closed, depending on
the weather, humidity and altitude abo e sea le el. To
richen turn the needle counterclockwise, to lean turn the
needle clockwise.
The Low-Speed Needle
The “low-speed” needle is the screw in the middle of the
throttle arm. It controls the fuel to air mixture at low throttle
settings. There is a simple way of adjusting the low-speed
needle correctly called the “pinch test.” With the engine at
idle, pinch the fuel line and listen to how the engine speeds
SECTION 8: CARBURETOR SETTINGS
SECTION 7: FINISHING
12

up or slows down. If the engine increases its speed for
about 2 or 3 seconds and then loses speed, the needle is
set correctly. If the engine loses RPM quickly, it is set too
lean and the low-speed needle needs to be opened
(counterclockwise) to richen the mixture. Pinch again to
check the mixture. If the engine takes longer than 4 seconds
to slow down, lean (clockwise) the low-speed needle and
then pinch again to check the mixture.
The Throttle Stop Screw
On the front of the carburetor, there is a black screw. This is
called the idle stop screw. This increases or decreases the
idle RPM without changing the fuel to air mixture. The barrel
should be approximately 1.5mm (between 1/32" and 1/16")
from fully closed.
To insure long life and good performance from your Torq .12
engine, you MUST break-in the engine. The break-in period is
critical for long life of the internal parts of the engine. This
should be done o er the first 4 or 5 tanks of fuel.
Some Things To Remember During Break-In
1. Run with the body off. This will keep the engine cooler.
2. Keep the air cleaner on at ALL times
3. Run on a smooth, hard surface. An empty parking lot is
perfect.
4. Use the same fuel that you will use for normal running.
5. Resist the urge to accelerate and decelerate the buggy
quickly.
6. Break-in puts stress on the glow plug and you can burn it
out during break-in. Make sure you ha e an extra plug or
two on hand.
7. Do NOT o erheat the engine. You can check the head
temperature by using one of the temperature gauges that
are a ailable or by putting a drop of water on the top of the
cylinder head. If the water boils away immediately, shut off
the engine and allow it to cool. If it takes more than 5
seconds to boil away, the engine is at proper running
temperature for break-in.
Before running the engine, read the manual and watch the
engine ideo that came with this kit.
There are several simple steps to starting the engine:
1. Install a glow plug. This threads into the top of the cylinder
head.
2. Fill the tank - Fill the tank almost to the top. Lea e a little air
at the top of the tank.
3. Prime the engine - Use the primer button on the fuel tank to
force the fuel through the fuel line. Watch the fuel go
through the line and when it gets to the carburetor, press the
primer button once more to get fuel into the engine.
4. Open the high speed needle al e exactly 1-3/4 turns out
(counterclockwise) from fully closed. The high-speed
needle is sticking up from the carburetor inside the
brass housing. All of the carburetor settings are adjusted
with a flat bladed screwdri er. If you ha e pre iously run the
buggy, keep the same needle al e setting that you used on
your last run.
5. Start the engine by pulling the recoil - Use short, quick pulls.
DO NOT pull the recoil starter’s string to the end. You only
need 10 to 12 inches of pull to start the engine.
Sometimes it is helpful to start the engine at around half
throttle. Ha e a friend pull back on the throttle some while you
start the engine. This may be an indicator that the low speed
needle setting needs to be adjusted. When the engine starts,
immediately return the throttle to idle. If this is not done the
engine can o er-re and cause engine damage. If the engine
is difficult to turn over with the recoil starter, especiall if
it is brand new, loosen the glow plug a half turn before
starting the engine. This allows some compression to
escape, but the engine will still start. Make sure you
tighten the glow plug after the engine starts. If the recoil
starter is still difficult to pull, the engine is flooded – there is too
much fuel inside the engine. Remo e the glow plug and air
cleaner, then turn the engine upside down and pull the recoil 5
or 6 times. This will clear the engine of fuel, and you will notice
the recoil pulls easier. Replace the glow plug and repeat the
starting procedure.
Fuels
Use fuels that are specially formulated for car and truck
engines. DuraTrax Red Alert fuel is specially formulated for
buggy engines like the Torq .12.
How To Stop Your Engine
You may ha e been wondering how to stop the engine. All you
ha e to do is pinch the fuel line that runs to the carburetor and
from the bottom of the fuel tank. Pinching this will restrict the
fuel flow and the engine will quit within a few seconds.
The First Tank
Your first tank of fuel should be running the buggy at a ery rich
high-speed needle al e setting. This allows the fuel to carry as
much oil as possible into the engine to lubricate the internal
parts during the break-in.
1. Open the needle al e 1-3/4 turns from fully closed
(counterclockwise). This is factory set already, but check it
to make sure. When closing the high-speed needle, close
the needle until you feel some resistance. DO NOT
o ertighten or you will damage the engine.
2. Start the engine.
3. Once the engine is started, open the high-speed needle
al e around 1/8 turn at a time, finding the setting where
the engine just barely runs. This may take a few times
adjusting the needle, running the buggy away from you
and back, then adjusting the needle. The buggy will
perform sluggishly and stall from time to time - that is
normal.
4. Run the buggy back and forth at medium speeds, slowly
accelerating and decelerating the buggy.
5. After a minute or two of running, make sure the engine is
not o erheating by putting a drop of water on the cylinder
head and watching it boil away. If it boils away
immediately, stop the engine and allow it to cool. Open the
high-speed needle around a 1/4 turn before starting again.
This is a good habit to get into e ery time you run to
ensure that the engine does not o erheat during any run.
Looking at the smoke that comes out the exhaust is also
an indicator of how rich or lean the engine is running. If
there is a good amount of smoke coming out of the
exhaust, then chances are good that you are running rich.
6. Run the buggy back and forth at a medium speed until the
tank is almost out of fuel. Do not allow the tank to run out
of fuel. This leans out the engine and can cause
o erheating (See How To Stop Your Engine).
SECTION 10: RUNNING THE ENGINE
SECTION 9: BREAKING-IN THE ENGINE
13

7. Stop the engine and allow the engine to cool before the
second tank. This normally takes around 10 minutes.
Tanks 2-5
Turn in the needle al e (clockwise) around 1/12 turn from the
pre ious setting. Run the buggy back and forth. You should
notice that the buggy will perform better during each run. Stop
the buggy periodically to check for o erheating. If it is too hot,
stop the engine. Wait for it to cool, then open up the needle
al e and restart. After the 5th tank, you should be near to the
peak performance of the engine.
10 Wa s To Ensure A Long Life From Your Engine:
1. Keep your engine clean. Dirt will act as insulation on an
engine. It will not be able to shed heat as easily. Use a
good air filter to keep dirt out of your engine and clean it
often.
2. Do not o er-lean your engine.
3. Do not run your engine with little or no load. Don’t throttle
up the engine to full throttle when the wheels are not in
contact with the ground.
4. Do not o erheat the engine. This goes along with keeping
it clean and not o er-leaning the engine.
5. Do not use a fuel with a low oil content. Make sure you use
a fuel from a reputable manufacturer, such as DuraTrax
Red Alert.
6. A oid using old fuels in the engine. Always run all of the
fuel out of the engine. After running for the day, use an
after-run oil and work it into the engine by turning the
flywheel or pulling the engine recoil slowly.
7. Do not use a fuel with a nitromethane (often called nitro)
content o er 20%.
8. Do not scratch the piston or cylinder slee e. A oid
jamming something into the exhaust port when remo ing
or re-installing the clutch or flywheel. Use a special tool
called a crankshaft locking tool, which is installed in the
glow plug hole.
9. Do not use silicone sealer on the engine joints. Silicone
sealer contains acetic acid, which is corrosi e if it gets
inside your engine.
10. Do not allow any water inside the engine. This sounds
easy, but temperature changes can cause condensation
inside the engine. This is a good reason to use an after- run
oil. Store your engine inside the house, not in a garage
or
shed where there will be temperature
extremes.
If you are having problems with your engine consult the
engine troubleshooting flow chart on page 16. The
following are some potential problems.
Glow Plug
The glow plug is an item that will wear out and need
replacement from time to time. It is a good idea to remo e the
glow plug before your first run, heat it and see how well it
glows. You should see a bright orange glow from the filament.
If a coil or two will not glow or the plug will not glow at all,
replace the plug. If the engine quits when you remo e the glow
starter, the plug might need to be changed, although this may
be because you are running too rich and need to screw in your
high-speed needle some. Look at the glow plug when you are
running the engine. If you see some bubbles coming from
around the plug, replace the glow plug (copper) gasket, or both
the plug and gasket. The only real way to test a glow plug is to
replace it. Make sure you ha e a spare plug or two on hand
e ery time that you run the Maximum BX.
Fuel
Fuel can go bad. The main ingredient in model fuel is
methanol, which is basically an alcohol. Alcohols can absorb
water out of the air, so keep your fuel jug capped at all times.
Store your fuel out of the sunlight and in a cool place. Bad fuel
is one of the most difficult problems to diagnose in engines. If
you ha e tried e erything you can think of to remedy an engine
that is not running correctly, try using some fresh fuel.
Fuel line is susceptible to pinhole leaks. You cannot see the
hole in the fuel line, but if you see air bubbles in the line going
to the carburetor, replace the fuel line. Another symptom of a
leak in the fuel line is a surging engine. The properly tuned
engine will surge when the air bubbles hit the carb. It is
basically leaning out the mixture.
To keep dirt out of the engine, use an inline fuel filter on the fuel
line running from the fuel tank to the carburetor. Dirt can get
caught in the needle seat and cause an inconsistent running
engine. If you suspect that some dirt has lodged itself in the
carb, remo e the needles and clean the carb
with denatured
alcohol or fuel. It can help to use
compressed air to blow out the
fuel passages as well. Dirt can get into your carburetor and
engine through the air filter. Ensure that your air cleaner has a
good seal to the top of the carb. Periodically wash the air
cleaner foam element and re-oil the filter. Any air cleaner that
has a torn element or a bad seal should be replaced
immediately.
Overheating
One of the worst things you can do to your engine is o erheat
it. The oils that lubricate the engine are carried in the fuel. If
your engine is set too lean, there will not be enough oil in the
engine to lubricate the internal parts. This will cause premature
wear in the engine and cause damage. We ha e talked about
o erheating in other parts of this manual, but we want to stress
the proper techniques to check for o erheating. The easiest
way of checking the temperature of the cylinder head is using
one of the a ailable temperature gauges. This will gi e you a
direct reading of the cylinder head temperature. Do not let the
head temperature exceed 220° Fahrenheit (104° Celsius).
Another way of checking the head temperature is to put a
drop
of water on the cylinder head. If it boils away
immediately, the
high-speed needle is set too lean. If the water boils away in
3-5 seconds, the engine is within proper operating temperatures.
If the water boils away longer than 5 seconds, the mixture is set
rich which is preferable when breaking in the engine.
Otherwise lean the mixture some and retest after a minute of
running.
Ride Height: This refers to the clearance between the ground
and the chassis, both at the front and the back of the buggy.
The general rule is to ha e the suspension arms perfectly le el
when the car is at rest. To determine the ride height, drop the
buggy from around 6"-12" abo e flat ground. Drop the buggy,
making sure it drops flat. Check where the suspension arms
come to rest. You can adjust ride by mo ing the spring
adjusters on the shock, which are at the top of each shock
spring, until the arms are le el after the drop test.
Toe-In Toe-Out: This refers to the angle of the front tires when
iewed from abo e when the suspension arms are le el. If the
fronts of the tires angle in, it is called “toe-in” and if the fronts
of the tires angle out, it is called “toe-out.” This is adjusted by
turning the steering rods - the rods that run between the front
SECTION 12: PERFORMANCE TUNING
SECTION 11: ENGINE MAINTENANCE
14

hub and the ser o sa er. These are turnbuckle type, which
means you do not ha e to remo e the rods to make
adjustments in length. Turning the rod in one direction will
lengthen, turning the rod the opposite direction will shorten.
Normally a small amount of toe-in is used to make the buggy
track straight at high speed. Too much toe-in will make the
buggy difficult to turn as well as reduce the o erall top speed
because of tire scrub. Sometimes a small amount of toe-out will
be used to help the steering. As a general rule use a small
amount of toe-in.
Camber: Camber is the angle of the tops of the tires when
iewed from the front. Negati e camber is when the tops of the
tires are angled towards the center of the buggy. Positi e
camber is where the tops of the tires are angled away from the
center of the buggy. Positi e camber is ery rarely used, if e er.
A small amount of rear negati e camber is helpful to increase
traction in the rear. Negati e camber at the front will increase
stability. Camber adjustments can be made on the Maximum
BX by turning the “camber rods,” which are the upper links on
the suspension. The camber links are also turnbuckle type.
Lengthening the camber rod will add positi e camber and
shortening the camber rod will add negati e camber.
Shocks: Changes in shock oils, springs, and pre-load on the
springs can dramatically change the way the car handles. A
thicker shock oil will make the buggy turn faster but reduces
o erall traction and handling o er bumpy surfaces. Thinner oil
will increase traction at the expense of steering response and
the car will tend to roll more. In general, shock oils between 20
and 40 weight will be best for your buggy. You should
experiment some to see what oils work best for your track and
dri ing style. Shock springs affect the rate that the suspension
rebounds from a bump. We ha e supplied soft springs that
work under most conditions. Other springs are a ailable from
DuraTrax. Pre-load on the springs means that the springs are
already compressed some so that the suspension will rebound
faster. Sometimes you will want to pre-load one side when the
track has turns all or mostly in one direction, for instance an
o al track. It will also increase the ride height.
Slipper Clutch: The slipper clutch is attached to the spur gear
on your buggy, the large gear on the outside of the
transmission. This clutch will slip when too much power is sent
to the wheels. It has adjustable tension by turning the nut on
the shaft. This is designed to maximize traction on arious
surfaces by slipping before the wheels do. To adjust the slipper
clutch, run the buggy on the surface you plan to race. If the rear
wheels spin when full power is applied from a stop, loosen the
nut until the wheels do not spin any more. If the wheels do not
spin, tighten the nut until the wheels spin and then loosen the
nut some.
Before Each Run
• Check for loosened screws on the buggy. Engine ibration
will loosen some of the screws, particularly in the engine
mount area. Use thread lock on screws that thread into
metal parts or use a metal nut.
• Inspect the air cleaner for a torn or damaged element. Also
look for dirt in the air cleaner element and wash it if
necessary.
• Check the suspension and dri e train for binding.
• Inspect all of the wires for damage. Also check the
connectors to make sure all of them are tight and in the
proper place.
• Check the fuel tank and fuel lines for leaks.
• Before starting the engine, turn on the radio and make sure
the ser os mo e easily and in the right direction.
• Before running always check the condition of your radio
system batteries and replace/recharge if necessary.
After Each Run
• Drain the fuel tank of any lefto er fuel. DO NOT return it to
your fuel jug.
• Put some after-run oil in the carb and turn the flywheel
se eral times to work the oil into the engine. This will protect
the engine from rusting, especially when stored for a long
period of time.
• Check again for loosened screws.
•CLEAN the buggy. Wipe off any oils that ha e collected on
the chassis, engine end exhaust. Oils will attract dirt on the
next run.
SECTION 13: MAINTENANCE TIPS
15
0" 1" 2" 3" 4" 5" 6" 7"
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180
Inch Scale
Metric Scale (mm)

ENGINE TROUBLE SHOOTING
The engine starts
Does the engine
turn o er easily?
Does it run
continuously?
Is fuel getting to
the engine?
Check for clogging in
the carburetor or fuel
line. Press the
primer pump and
check for fuel
spraying out of the
fuel line. If so,
replace the fuel line.
Is fuel in the
fuel line?
Is the glow plug
red hot?
Check the high speed needle
setting and prime the engine.
Is foreign matter
clogging the fuel
tank or fuel line?
Is the battery for
the glow plug
clip charged?
It should be
ready to go.
Is the high
speed needle
setting 1 to
1-1/2 turns out
from closed (if
the engine is
broken-in?)
Try starting the
engine again.
NO
NO
NO
NO
YES
YES
YES
YES
YES
Does the engine
quit when the
glow plug clip is
remo ed?
YES
YES
Clear the engine
of fuel.
NO
Reset the high
speed needle.
YES
NO
Replace the
glow plug.
Check that the
pressure line is
connected to the
muffler. The fuel
may be bad.
The engine does not start
NO
Does the engine
turn o er easily
with the glow
plug remo ed?
The engine may
be flooded.
Clear the engine
of fuel.
YES
Check that
nothing is
caught in the
engine. Check
that the the
pull starter
operates
smoothly.
NO
Press the
primer pump
and check for
fuel spraying
out of the fuel
line through a
small hole. If
so, replace
the fuel line. YES
Remo e the
obstruction from
the fuel tank or
fuel line.
NO NO Charge or
replace the
batteries.
YES
Replace the
glow plug.
Try starting the
engine again.