Sportwerks Mayhem ST Installation and operating instructions

Sportwerks Mayhem™ ST RTR
Assembly and Operation Manual
Length: 19.4" (492mm)
Width: 16.5" (419mm)
Track Front: 16.3" (415mm)
Track Rear: 16.5" (419mm)
Wheelbase: 13.5" (342mm)
Weight: 9.5lb (4309 g)
Gear ratio: 4.09:1
Specifications:

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Thanks for your purchase of the Mayhem™ ST.
Hang on! You’re about to discover just how much
fun trying to tame an overpowered 1/8-scale
stadium truck can be. In just minutes you’ll be
ripping up the dirt, at speeds over 40 mph.
The Mayhem ST chassis is based on the race
winning design of the Sportwerks™ Mayhem
Pro racing buggy. Professionally built and hand
assembled by the Sportwerks team. The shocks
and differentials are pre-filled with the correct
lubes for optimum handling and performance. The
Mayhem ST RTR comes assembled with radio,
engine, and exhaust installed. All that’s required to
make it race-ready is to install a 6-cell pack in the
handheld starter and 8 “AA” alkaline batteries (not
included) in the transmitter. Charge the receiver
pack with the battery charger supplied with your
kit. The initial charge should take about 4 hours.
Partially discharged batteries will take less time.
Note: Do not leave unattended while charging.
If the battery becomes warm it is fully charged;
discontinue charging immediately. Overcharging may damage the battery.
Good luck, have fun and enjoy the excitement of RC with your new Mayhem ST.
Sportwerks Product Development Team
Introduction

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Replacement Parts
Center Differential .................................................................................... 14
Front/Rear Differential .............................................................................. 15
Front and Rear Shocks ............................................................................ 16
Steering Bellcrank .................................................................................... 17
Front Suspension ..................................................................................... 18
Front Gearbox Mount ............................................................................... 19
Center Drive Shaft - Front ........................................................................ 20
Rear Suspension ...................................................................................... 21
Rear Gearbox Mount ................................................................................ 22
Center Driveshaft - Rear .......................................................................... 23
Chassis .................................................................................................... 24
Radio Tray Assembly ............................................................................... 25
Engine/Clutch/Air Fliter ............................................................................ 26
Fuel Tank Assembly ................................................................................. 27
Wheel and Tire Assembly ........................................................................ 28
Replacement Parts List ............................................................................ 29
Instructional
Introduction ............................................................................................... 2
Table of Contents ....................................................................................... 3
Required Equipment .................................................................................. 4
Recommended Tools ................................................................................. 5
Quick Start ................................................................................................. 6
Engine Starting and Break-in ..................................................................... 8
The Sportwerks Carburetor ........................................................................ 9
Starting the Engine .................................................................................. 10
Adjusting the Carburetor .......................................................................... 11
After Run Engine Maintainance ................................................................ 12
Brake Linkage Setup ................................................................................ 13
Table of Contents

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Additional equipment required for
assembly (not included)
• 6-cell 7.2 volt car pack
(DYN1000 recommended)
• 8 “AA” Alkaline batteries
Additional items needed to operate
• Glow igniter
• Air filter oil
• Car fuel
• Fuel bottle
Note: Dynamite® offers a starter pack that includes
the above items plus it includes extra glow plugs, a
plug wrench and fuel line. (DYNSTART2).
Required Equipment

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While the Mayhem™ ST comes assembled and no
tools are required, you’ll find the following tools helpful
when maintaining your Mayhem ST:
Recommended Tools
• 1.5mm hex wrench
• 2mm hex wrench
• 2.5mm hex wrench
• 3mm hex wrench
• Small flat screwdriver
• #1 Phillips screwdriver
• Needle-nose pliers
• 8mm nut driver
• Lexan scissors
Recommended Tools

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Step #1
The receiver pack included with your Mayhem™ ST will
require charging. Open the radio box and remove the
receiver pack. Plug the battery lead into the supplied
charger. The initial charge should take approximately 4
hours. Partially discharged batteries will take less time.
Note: Do not leave unattended while charging.
If the battery becomes warm it is fully charged,
discontinue charging immediately. Overcharging
may damage the battery.
Step #2
Install 8 “AA” batteries in the transmitter noting the
proper direction of each cell.
Step #3
Insert the antenna tube in the top of the radio box.
Feed the receiver antenna through the tube until several
inches extend out the top. Install the antenna tip.
Quick Start
When the battery is warm to the touch, reinstall the
battery into the battery box and connect the battery
to the open plug.
Note: Because of the voltage required to power
the steering servo, we recommend only using
6-volt battery packs like the one supplied and
only powered though the Y-harness in channel 2
of the receiver.

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Step #4
Install a charged 6-cell 7.2-volt battery in the starter
and attach the plug.
Step #5
Turn on the transmitter and then the receiver. Check
to make sure that the servos are operating correctly
and that the carburetor closes when the throttle trigger
is released.
Step #6
Apply air filter oil (not included) and spread the oil
uniformly onto the air filter allowing it to saturate the
foam element.
Congratulations! Your Mayhem™ ST is
ready to rip!
Quick Start Guide

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Your First Runs
If this is your first gas car, we highly recommend that
you have an experienced gas car driver help during
the first startups and runs. He will be able to help you
properly adjust your engine for break-in and then tune
your engine for reliable performance.
Before attempting to start your new truck, be sure to
read this section and fully understand each step before
starting your engine. Pay particular attention to the
needle settings recommended for starting and to the
break-in procedures suggested to the right.
Fuel and Glow Plug
Note: Using the proper fuel and glow plug is vital
in achieving reliable performance and is a must for
long engine life. You must use fuel and glow plugs
that are specifically designed for model car use.
Never use any type of model airplane glow fuel!
We recommend a high-quality car fuel containing
20% nitro methane (Blue Thunder 20% Sport fuel is
recommended). A glow plug is included that is ideal
for breaking-in your new engine. During the break-in
process, it’s not uncommon to go through one or two
glow plugs, as microscopic particles of metal (from the
cylinder/piston wearing in) bond themselves to the plug
element causing glow plug failure. We recommend the
Dynamite® MC-59 Glow Plug (DYN2508) as the best
replacement glow plug for this engine.
Air Filter
A clean, properly oiled air filter is a must to keep dirt
out of the engine. Using a quality air filter oil like
(DYN2502), spread the oil uniformly onto the air filter
allowing it to saturate the foam element.
Engine Starting and Break-in

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The Sportwerks™ .26 engine features a slide-valve
carburetor and includes three inserts of various
diameters. These carburetor inserts are used to alter
the power curve of the engine. The three diameters
included have the following effect:
6.5mm – Gives smooth controllable acceleration;
offers best fuel mileage; best-used for
slick tracks/surfaces or beginning
gas drivers.
7.5mm – Develops good mid-range power; easier
to control than the 9mm insert; best for
medium traction, average-sized tracks/
areas.
9mm – Offers explosive, sometimes difficult to
control acceleration; uses the most fuel;
used only for high traction, large track/
open areas; for expert drivers only.
Setting the needles
While the needles are preset at the factory, it’s a good
idea to verify that the needles are properly set slightly
rich for break-in. Following are the recommended
starting settings:
High- Speed Needle: 3 1/2 turns out
(counterclockwise) from closed
Low- Speed Needle: 2 turns out
(counterclockwise) from closed.
Note: When checking the adjustment of the low-
speed needle, it is crucial that the throttle slide is
closed completely and that you do not over-tighten
the needles. When you feel resistance, immediately
stop turning. This is the closed position.
Starting Your Engine For The First Time
Break-in
The first startups and the first several minutes that
your engine is running is the most critical time of
its life and, in many ways, dictates how well it will
perform and how long it will last.
During the first runs, when the engine starts, the
exhaust should emit blue/white smoke, indicating
that the engine is rich (a good thing during break-in).
During the first tank of fuel, you may wish to set a
higher than normal idle speed in order to keep the
engine from stalling. Drive your truck while “blipping”
the throttle and avoid operating the engine at full
throttle for more than 2–3 seconds at a time. Run
the entire first two tanks of fuel in this manner. After
the first two tanks of fuel, begin leaning out the high-
speed needle valve 1/8 turn at a time. It generally takes
about 5 or 6 tanks of fuel before you’d want to start
tuning for “maximum” power. Patience during break-in
will be rewarded with an engine that performs reliably
and to its maximum power potential. Remember, glow
plug failure is a common occurrence when breaking
in a new engine. To test your plug, let the engine idle
at a properly adjusted low-speed needle setting with
the glow igniter attached. Then, remove the igniter.
If you hear no appreciable change in engine rpm, the
plug is still good. If the engine loads up and the rpm's
decrease, it’s time to replace the glow plug.
The Sportwerks Carburetor
High-Speed
Needle Valve
Low-Speed
Needle Valve
Idle Screw
Lean
Lean
Carb Insert

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Step 1
Fill the tank with fuel
Step 2
Turn on the transmitter and receiver and confirm that
the radio system is working properly.
Step 3
Attach the glow driver to the glow plug.
Step 4
Fully insert the electric start shaft into the back
of the engine. Press the start button for
ten seconds then stop. The engine should turn
over but likely won’t yet start. Continue these
ten second starting attempts several times until the
engine starts.
Note: Should the engine not turn over when
the electric starter is applied, the engine may
be flooded (hydro-locked). Excess fuel in the
combustion chamber can prevent the piston from
traveling through its full range of compression,
effectively “locking up” the engine. Should this
occur, remove the glow igniter from the plug and,
using a glow plug wrench (DYN2510), remove the
glow plug and turn the model upside down. Give
the starter a few short blips to clear the fuel from
the combustion chamber then re-install the glow
plug and try again.
You may find it necessary to “blip” the throttle on the
transmitter (applying throttle on/off) while trying to
start the engine, as new engines are more difficult to
start due to the tight piston/cylinder fit.
Never start an engine above 1⁄4 throttle or damage to
your engine could occur!
Starting the Engine

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Adjusting the Carburetor
Tuning your Engine
When tuning the needle valves for maximum
performance, adjust them in small increments, 1⁄16
turn at a time. An engine should not be run too lean;
doing so severely shortens the life of the engine. When
an engine is set too lean, it will run very strong at first
but will soon begin to sag and hesitate or stall when
accelerating. The best way to tune an engine is by
using an infrared temperature gauge, but you can also
use water to check the head temperature. (Refer to
“Fine Tuning Your Engine”)
Fine-Tuning Your Engine
As you gain experience, you’ll be able to tune your
engine based on the engine’s sound and feel during
acceleration and at full throttle. Until you’ve developed
this skill, we recommend the following method of
engine tuning.
Start your engine and drive your truck aggressively for
about two minutes.
Place a drop of water on the cylinder head.
If the water sizzles away (evaporates immediately), the
needle setting is too lean.
A correct needle setting will result in the
water evaporating slowly, in about 5–10 seconds. If
the water does not evaporate, the needle setting is too
rich. Lean the high-speed needle 1/8 of a turn and run
the engine again, adjusting the needle setting to get the
desired evaporation rate of 5–10 seconds. Check the
temperature each time you change the needle mixture.
Do not let the engine overheat, as this will damage
the engine!
Tuning the Low-Speed Needle
The low-speed needle (also referred to as
the idle mixture or idle needle) should be set after
you’re satisfied with the high-speed needle setting.
After achieving the engine’s proper operating
temperature, reduce the engine throttle to idle for about
15 seconds. Now pinch the fuel line with your fingers
close to the carb fuel inlet nipple while carefully
listening to the engine rpm. If the engine dies
immediately without an increase in rpm, the low-speed
needle is set too lean.
If the rpm’s increase dramatically and then the engine
dies, the setting is too rich.
The ideal setting results in the rpm ’s increasing a
slight amount (about 200 rpm’s) after pinching the fuel
line before dying.
Setting the Idle rpm
The last setting to be made is the idle rpm. Turning
the idle stop screw clockwise increases the idle speed;
whereas turning the screw counterclockwise will make
the engine idle at a lower rpm. Ideally, the engine
should idle just fast enough to give a reliable idle but
not engage the clutch and, of course, never flame out.

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After you’re finished racing for the day, it’s important
to empty the fuel tanks and run the remaining fuel
from the engine. Continue to try to start the engine for
several seconds after it will no longer fire to ensure
that all fuel is out of the engine. Put several drops
of after run oil in the carburetor and turn the engine
over on the starter box for several seconds to coat the
internal engine parts with after run oil.
Clean the air filter regularly, using warm soapy water
then allowing it to air dry before applying air filter oil.
Keeping your air filter clean and oiled is vital to the life
of your engine.
After Run Engine Maintainance

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Step #1
Turn on the radio system and adjust the throttle trim to
the desired neutral position.
Step #2
Install the arm with attached linkage on
the servo adapter such that the brake linkage
will be parallel to the arm with the brake ball
links attached.
Step #3
Be sure the ball links are snapped onto the front and
rear brake and on the carburetor.
Note: It may be necessary to adjust the position of
the throttle return spring to allow the ball link to
snap on the ball.
Step #4
Adjust the position of the return spring collar until the
correct tension is achieved. With the throttle at neutral,
the spring should just close the carburetor barrel with
light tension.
Step #5
Loosen the setscrew in the blue knurled knob and slide
the knob such that it just contacts the molded pivot on
the arm; retighten the setscrew.
Step #6
Adjust the full throttle position with the programming
in your transmitter such that the carburetor is full open
just as the trigger reaches the full throttle position. By
rotating the blue throttle knob, you can now precisely
adjust the throttle dead band (the amount the throttle
moves before the carburetor barrel actually opens)
without disturbing the spring preload settings.
Step #7
With the throttle at neutral, pull the front (silver
knob) brake linkage through the molded pivot such
that the front brakes are slightly applied. Loosen the
setscrew on the silver adjusting knob and slide it into
position such that it just contacts the molded pivot and
retighten the setscrew.
Step #8
With the throttle at neutral, pull the rear (red knob)
brake linkage through the molded pivot such that the
rear brakes are slightly applied. Loosen the setscrew
on the red adjusting knob and slide it into position
such that it just contacts the molded pivot and
retighten the setscrew.
Step #9
Cut off the excess lengths of linkage to clear the body.
By rotating the silver adjusting knob, the front brakes
can be accurately adjusted; rotating the red knob will
affect the rear brake adjustment.
Initial Brake Adjustment
With the radio on and the throttle trim at neutral,
adjust the front brake using the silver adjusting knob
until it just starts to apply pressure to the front tires.
Now back the front brake off one turn. Adjust the rear
brake using the red adjusting knob until it just starts
to apply slight pressure to the rear tires then back the
rear brake off 1/2 turn. These are the neutral starting
settings for the front and rear brakes.
Brake Linkage Setup
Although the brake linkages are pre-set at the factory,
it may be necessary to adjust them if you take the
vehicle apart for cleaning or maintenance. The
following covers the installation and adjustment of
the linkages in such instances.

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90
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Center Differential

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72
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82 79
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145
72
Front/Rear Differential

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6964
6963
68 6967
68 69
68 69
68 6967
68 6930
71
7069
69 7049
48
70 69
61 69
6927
6935
7069
69 70
3469
65 69
6968
62 69
Front and Rear Shocks
61 69
6927
6935
7069
6934
6968
6964
69 70
69 70
65 69
62 69
6963
68 6967
68 69
68 69
68 6967
68 6930
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7069
69 7049
48

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130
2
Steering Bellcrank

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138
102 50
42
29
24
133
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13
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55
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99 100
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23 99
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50
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29
Front Suspension

Page 19
139
35
137
24
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24
137
35
19
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48 112
40 112
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105
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136
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39 112
16
49 112
48 112
Front Gearbox Mount

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14
Center Drive Shaft - Front