T-MAXX 3.3 OWNER’S MANUAL • 15
THE TRX 3.3 RACING ENGINE
THE AIR FILTER
The TRX 3.3 Racing Engine in this model is equipped with a specially
designed two-stage air filter to deliver maximum filtering efficiency and
performance while protecting your engine from dust and dirt during
extended operating conditions. Use only the supplied filter.
You will not
improve engine performance by switching to an aftermarket filter
, and
you may risk engine damage due to poor filtration.
The two-stage TRX Racing Filter consists of the following components:
1. A rubber filter Base
2. A 3-piece plastic housing
3. A “pre-filter” element
4.
A “primary” filter element
You must clean the outer pre-filter after every hour of run time, even if the
filter looks clean.
The primary filter element inside must be cleaned after
3-4 hours of run time. These intervals include the break-in time. Clean
your air filter after break-in.
Dust (which is often too fine to see) and dirt
constantly move through the filter anytime the engine is running. Even if you
can’t see dirt on the filter, it is present inside the foam after any amount of
run time. If you exceed the recommended cleaning intervals, your engine will
be damaged. Engine damage or wear due to dirt ingestion is easy to detect,
and one of the top causes of premature engine failure.
Pre-Filter Cleaning Instructions (every hour of run time)
1. Remove the clip from the air filter
and remove from the metal hanger.
Remove the air filter assembly from the
carburetor bore by pulling the entire
filter assembly firmly to the side to
release it. Do not pull straight up.
2. Remove the pre-filter element.
3. Clean the pre-filter element by
thoroughly washing the foam element
in hot soapy water (dishwashing detergent works well). Repeat twice.
4. Thoroughly dry the pre-filter element with a clean towel.
5. Oil the foam element with air filter oil. Use Traxxas filter oil (part# 5263)
or a high-quality, special-purpose foam filter oil like what is used for
off-road motorcycle and ATV engines. This type of filter oil is available
at motorcycle pro-shops. Apply a total of 24 drops of Traxxas air filter
oil, evenly distributed between the top, bottom and sides of the filter
element. Squeeze the filter element repeatedly to help spread the oil
throughout. The filter element should be evenly colored by the oil. Even
color indicates that the oil is spread evenly. Do not squeeze out excess
oil. Note: Do not use the air filter oil for anything other than the air filter.
It is not meant to be a lubricant.
6. Reassemble the filter and install it on the engine, making sure the rubber
filter neck fits securely on the carburetor with no gaps or air leaks.
Primary Filter Cleaning Instructions (every 3 - 4 hours of run time)
1. Remove the clip from the air
filter and remove from the metal
hanger. Remove the air filter
assembly from the carburetor bore
by pulling the entire filter assembly
firmly to the side to release it. Do
not pull straight up.
2. Remove the pre-filter element.
3. Remove the 3x6mm screw in the end of the filter housing. Remove the
front housing and the primary filter element.
4. Clean the filter parts by thoroughly washing in hot soapy water
(dishwashing detergent works well). Repeat twice for the foam
filter elements.
5. Thoroughly dry the foam pre-filter and primary filter elements with a
clean towel. Dry the remaining filter parts.
6. Oil the foam pre-filter with 24 drops of air filter oil, and the primary filter
element with 30 drops of air filter oil.
7. Reassemble the filter and install it on the engine, making sure the rubber
filter neck fits securely on the carburetor with no gaps or air leaks.
THE CARBURETOR
Understanding the Carburetor Adjustments
The carburetor performs
several functions. It controls
the engine’s speed by
restricting the intake of air
and fuel into the engine. It
atomizes the fuel (suspends
the fuel droplets in the air)
and also controls the air/fuel
ratio of the mixture entering
the engine (how much air for
a given amount of fuel).
To help provide a better
understanding of engine tuning and why it’s necessary, the following is
a brief explanation of the air/fuel combustion process that takes place
inside the engine.
In order to create the cylinder pressure that results in power, the engine
burns the air/fuel mixture. Both air and fuel, in correct amounts, are
needed for proper combustion. It is the carburetor’s job to mix the air
and fuel together (atomize the fuel), in the correct proportion for the best
possible combustion. This is the ideal air/fuel ratio. The ideal air/fuel ratio
required for the engine remains roughly constant. Due to variations in
atmospheric conditions (temperature, humidity, altitude etc.) fuel flow
adjustment valves (called fuel mixture needles) are required to meter
the fuel and maintain the ideal air/fuel ratio in these ever-changing
conditions. For example, colder air is more dense (more air molecules)
for a given volume of air and therefore requires more fuel (more fuel
molecules) to maintain the correct air/fuel ratio. Warmer air is less dense
(fewer air molecules) and therefore needs less fuel to maintain the correct
air/fuel ratio. The tuning needles are there to adjust how much fuel is
made available for the carburetor to mix with the available
air (atomization).
The Fuel Mixture Needles
The amount of fuel metered and atomized by the carburetor is controlled
by the two mixture needles, the high-speed needle and the low-speed
needle. The low-speed needle is used to meter the fuel used by the
engine at idle and low rpm (part-throttle) engine speed. The high-speed
needle is used to meter the fuel when the throttle is open from part
throttle to wide-open throttle (WOT). Two needles on the TRX 3.3 Racing
Engine provide precise control of the air/fuel ratio across the engine’s
entire rpm range.
Air
Fuel
Cold Air (More Dense)
Warm Air (Less Dense)
See page 21 for more information on how air density affects
engine tuning.
Pull to the side to remove assembly
Pull to the side to remove assembly
