REVO 3.3 • 23
Tuning the engine means finding the
perfect balance between the two;
excellent power to meet your needs
while maintaining good lubrication
for long engine life.
The optimal fuel
mixture setting is rich
to provide a
safety margin against having a lean
condition if some variable changes
(such as the temperature from one
day to the next).
General fuel mixture settings are
measured by the number of turns
the needles are turned out from fully
closed. The fuel mixture settings
have been pre-set from the factory
to typical break-in settings. Do
not readjust your carburetor from
the factory settings until after the
engine is started and running, and
you have been able to observe the
engine running to assess what minor adjustments may be required
to compensate for fuel, temperature, and altitude. Adjustments are
usually made in 1/8 or 1/16-turn increments. If the engine sticks at top
dead center (TDC), see page 38 for instructions on freeing the engine.
The Idle Speed Adjustment
The idle speed screw controls the closed position of the throttle slide.
When the throttle servo is in its neutral position, the throttle slide
should be stopped against the idle adjustment screw. Always use
the idle speed adjusting screw to control engine idle. Do not use the
throttle trim on the transmitter to adjust idle speed. The idle speed
should be set as low as possible and still maintain reliable running.
EZ-START ELECTRIC STARTING SYSTEM
The Traxxas EZ-Start brings the convenience of push-button electric
engine starting to your Revo. The EZ-Start consists of a hand-held control
unit and an on-board motorized starter.
• Power for the EZ-Start system comes from a 7.2-volt rechargeable
battery pack installed in the hand-held control unit.
• The engine glow plug is heated automatically by the EZ-Start system,
eliminating the need to keep up with a separate glow plug igniter.
• The voltage to the glow plug is kept constant, regardless of the load
placed on the starter by the starter motor.
• The “Glow Plug” LED (light emitting diode) on the control unit
indicates the condition of the glow plug.
• The “Motor” LED indicates the status of the EZ-Start electric starter motor.
• The cush drive mechanism in the drive unit prevents damage to the
gears caused by engine kickback.
• Smart Start
™
protection circuitry prevents damage to the motor by cutting
power if the load on the motor or other electronics exceeds safe limits.
Charging the EZ-Start Battery
The included charger can be used to charge
the included EZ-Start battery pack.
Do not
charge batteries inside of an automobile. Read
the Safety Precautions section of this guide.
1. Plug the charger into a 12-volt automotive
auxiliary power socket.
The charger is
compatible with 12-volt automotive
auxiliary power sockets only. The LED on the
charger will glow red to indicate it is ready
to charge a battery.
2. Connect the battery to begin charging.
Plug
the battery into the charger. The charger’s
LED will flash green, indicating that charging
has begun. The flashing green LED on the
charger indicates the charge progress.
3. Disconnect the battery
when charging is
complete.
When the
battery is fully charged,
the LED will light solid
green. The battery will
be warm in your hand.
Disconnect the battery.
See
Tuning Your TRX 3.3
Racing Engine
on page 27
for complete information on
adjusting the air/fuel mixture
and idle speed.
Factory Needle Settings
If your factory preset
carburetor adjustments have
been tampered with, use the
following settings:
• Set the high-speed needle to
4 turns out from closed.
• Set the low-speed needle so
the screw head (
red in Fig. A
)
is flush (even) with the end
of the slide (
yellow in Fig. A
).
Always use the factory
settings for initial starting.
Only use these settings when
the factory settings have
been lost.
Higher nitro requires a richer
fuel mixture. When running
33% fuel, richen your high
speed needle 3/4 turn if
previously running 20% nitro
and then re-tune the engine
for maximum performance.
Low Speed
Needle Adjustment
Fig. A
THE TRX 3.3 RACING ENGINE
2
CHARGE PROGRESS
x1
1 green flash
0 - 25% charged
x2
2 green flashes
25% - 50% charged
x3
3 green flashes
50% - 75% charged
x4
4 green flashes
75% or more charged
Solid green LED
100% charged
CHARGER LED INDICATION
MEANING
Solid Red LED
Ready for Charging
Slowly Flashing Green LED
Charging (see Charge Progress chart)
Solid Green LED
Battery Fully Charged
Flashing Red LED
Charger error
Note:
If there is a problem with the battery, such as a short circuit, the charger’s LED will flash red. Disconnect
the battery and unplug the charger from its power source to clear the error. Determine the cause of the error
before continuing.
Lean
Rich
1
2
3
Disconnected
Connected
Charged
