26 • NITRO RUSTLER
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°F 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°F during break-in. In weather
below 45°F, the TRX 2.5 Racing Engine will tend to run at lower
temperatures between 160 to 180°F (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°F 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°F.
If the water sizzles for only a few seconds, then it is likely that it is
over 220°F, 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°F.
If you insist on running your vehicle below 35°F, 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 up, and this can be harmful to the engine.
Follow the remaining break-in procedures as outlined in this Owner's
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.
ThE TRx 2.5 RacING ENGINE
