Advertisement
The TRX 2.5 Racing Engine
Tuning the TRX 2.5 for Best Performance
When adjusting the
low-speed fuel mixture,
The engine's performance depends on the fuel mixture. Turn the
it is very important to
mixture needles clockwise to lean the fuel mixture and
make several high-speed
counterclockwise to richen it. Leaning the fuel mixture will
runs with the S-Maxx
increase engine power up to the engine's mechanical limits.
between adjustments to
Never run the engine too lean (not enough fuel flow). Never
clear out any excess fuel.
lean the engine until it begins to cut-out or stall. Leaning the
Perform the pinch test
engine beyond the safe allowable limits will result in poor
immediately after. If the
engine is allowed to idle for
performance and almost certain engine damage. Indications
a long period of time, it
of an overly lean mixture include:
could "load up" with fuel and
give you an inaccurate
measurement from your
pinch test.
If any of these conditions are present, stop immediately and
richen the high speed mixture 1/4 turn. The engine will
For your convenience,
the low-speed needle
probably be slightly rich at that setting and you can then retune
has a positive stop that
for performance. Always tune for performance by starting rich
prevents it from being over
and moving leaner toward the ideal setting. Never try to tune
tightened and damaging the
from the lean side. There should always be a light stream of blue
needle and seat. This also
smoke coming from the exhaust.
provides an easy way to
gauge how many turns out
Before you begin tuning, the engine should be warmed up to its
from closed the low-speed
normal operating temperature and running slightly rich. All final
needle adjustment is set to.
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:
When tuning for
performance, watch
closely to notice when
there is no longer any
increase in speed or power
when the high-speed
mixture is lean. If you lean
High-Speed Fuel Mixture Adjustment
the high-speed mixture to
With the engine warm and running at a rich setting, gradually
the point that the engine
lean the high-speed fuel mixture in 1/16 turn increments. Make
cuts-out, hesitates, or stalls,
several high-speed passes with Revo after each adjustment to
you are well into the danger
zone and engine damage is
clear out the engine and note any change in performance. The
likely. Richen the high-speed
TRX-2.5 is extremely powerful. Remember to apply the throttle
needle 1/4 turn and retune.
gradually to prevent wheelies or loss of control. Continue this
procedure until there is no longer any performance
improvement.
34
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.
Sluggish acceleration with blue smoke coming from
the exhaust.
There is unburned fuel spraying from the exhaust tip
Leaning the high-speed fuel mixture increases performance
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
Richen the fuel mixture to the optimum setting by richening the
high-speed needle at least 1/8 turn counterclockwise and retest.
This setting will extend engine component life.
Advertisement
