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3. For the first tank of fuel, run the engine at 25%
throttle.
The engine should run very slightly rich. If not, stop the
engine by closing the throttle completely and pinching
the fuel line with needle-nose pliers… being careful
not to damage the fuel line or get the pliers near the
spinning propeller. Adjust the main needle and finish the
remainder of the first 10min break-in period.
4. Stop the engine and allow it to cool down completely.
Make sure the piston does not get stuck at TDC (top
dead center – at the top of the cylinder); rotate the
propeller by hand to move the piston to the bottom of
its stroke (BDC – bottom dead center).
5. Run the engine through several more heat cycles:
a) more tanks of fuel at 50% throttle (the engine
should still be running slightly rich), with complete
cool-downs.
b) more tank of fuel at 70% throttle (the engine should
be running crisply now), then complete cool-down.
During the final tank of fuel, vary the throttle and
check the crispness of the engine response.
EnginE tEmpERAtuRE
Throughout the break-in process, regularly check the
engine temperature to ensure it stays within the range
of 200–250°F. This is only a guideline and may vary from
engine to engine. The engine temperature and RPM should
be steady and not vary significantly; any significant changes
indicate that the carb settings require attention.
