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Winter Break-in Tips
During the break-in process, the piston
and sleeve wear into each other to form a
precise fit. The engine needs to heat up to a
temperature around 200 to 215 degrees to
allow the piston and sleeve to achieve this
fit properly. A precise fit between these two
components is critical for proper compression,
and optimum performance. If the engine
runs too cold during break-in, the piston and
sleeve will not expand to their appropriate sizes for break-in, and this can
lead to premature wear of these components. This wear may not become
apparent until after winter has past, and the engine is operated under
warmer running conditions.
• Warm the engine to approximately room temperature by removing
all fuel and storing the vehicle inside at room temperature until just
before starting the engine. An extremely cold engine can become
difficult to start.
• After the engine is running, it is important to keep the temperature of
the engine up around 200 to 215 degrees during break-in. In weather
below 45 degrees, the TRX 3.3 Racing Engine will tend to run at lower
temperatures between 160 to 180 degrees (when tuned at proper
break-in mixture settings). This is too cool for break-in. Do not lean the
fuel mixture to increase engine temperature! This will also decrease
lubrication and cause your piston/sleeve to wear prematurely.
• Wrap the cooling head with a paper towel, clean rag or sock to help
keep the engine running around the recommended 200 to 215 break-
in temp. If too much heat is contained, the engine can actually run too
hot. Make sure that you monitor the engine's temp closely for the first
couple of tanks until you get the right amount of cover for the cooling
head. This will, of course, depend on your current weather conditions.
Adjusting the cover up and down, exposing more or fewer cooling fins,
is a convenient way to regulate engine temps.
• For owners that do not have access to a temperature probe, a drop of
water on the cooling head (around the glow plug area) should slowly
sizzle for approximately 6 to 8 seconds around 200 to 210 degrees. If the
water sizzles for only a few seconds, then it is likely that it is over 220
degrees, and needs to cool down. If the water takes a long time or does
not evaporate at all, then the engine is too cool.
• We do not recommend that you operate your engine below 35 degrees
Fahrenheit. If you insist on running your vehicle below 35 degrees,
be aware that nitro engines may be very difficult to start and tune at
extremely cold temperatures. Also, at temperatures below freezing, nitro
fuel can actually begin to gel, and this can be harmful to the engine.
Follow the remaining break-in procedures as outlined in this Owners
Manual. This, along with the steps listed above, will ensure a good break-
in for your new nitro engine, and provide many hours of enjoyment.
High Altitude Operation: If you live in a high altitude region (5000
or more feet above sea level), the lower air density may require
you to lean your high-speed fuel mixture slightly from the factory
break in settings. Try this if you are experiencing difficult starting
or extremely sluggish engine performance at high altitude.
THE TRX 3.3 RACING ENGINE
TUNING YOUR TRX 3.3 RACING ENGINE
The engine's performance
depends on the fuel
mixture. Turn the mixture
needles clockwise to
lean the fuel mixture
and counterclockwise
to richen it. Leaning the
fuel mixture will increase
engine power up to the
engine's mechanical limits.
Never run the engine
too lean (not enough
fuel flow). Never lean the engine
until it begins to cut-out or stall.
Leaning the engine beyond the safe
allowable limits will result in poor
performance and almost certain
engine damage. Indications of an
overly lean mixture include:
•
Cutting out or sudden loss of power during acceleration.
• Overheating (temperature beyond 270° F at the glow plug).
• Little or no blue smoke coming from the exhaust.
If any of these conditions are present, stop immediately and richen the
high speed mixture 1/4 turn. The engine will probably be slightly rich at
that setting and you can then retune for performance. Always tune for
performance by starting rich and moving leaner toward the ideal setting.
Never try to tune from the lean side. There should always be a light
stream of blue smoke coming from the exhaust.
Before you begin tuning, the engine should be warmed up to its normal
operating temperature and running slightly rich. All final tuning adjustments
must be made to the engine at its normal operating temperature. You can
tell the engine is running rich by noting any of the following:
• Sluggish acceleration with blue smoke coming from the exhaust.
• Revo may not shift into second gear.
• There is unburned fuel spraying from the exhaust tip.
• Leaning the high-speed fuel mixture increases performance.
High-Speed Fuel Mixture Adjustment
With the engine warm and running at a rich setting, gradually lean
the high-speed fuel mixture in 1/16 turn increments. Make several
high-speed passes after each adjustment to clear out the engine and
note any change in performance. The TRX 3.3 is extremely powerful.
Remember to apply the throttle gradually to prevent wheelies or loss of
control. Continue this procedure until there is no longer any performance
improvement. If any one of the following conditions occurs, the fuel
mixture is already past the maximum safe lean setting:
1. There is no longer any performance improvement.
2. The engine begins to cut out at high speed (Danger!).
3. There is a sudden loss of power during acceleration (Danger!).
4. The engine begins to overheat. Symptoms of overheating include:
• Steam or smoke coming from the engine (not exhaust).
• Hesitation or stalling during acceleration.
• Popping or clattering sound when decelerating (detonation).
• Fluctuating idle speed.
• Temperature measurement above 270° F at the glow plug (A
temperature reading above 270° alone does not necessarily indicate
overheating. Look for other symptoms of overheating combined with
temperature for a more accurate warning).
REVO PLATINUM EDITION • 9
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