O.S. Engines FT-300 Gemini User Manual
Page 13
RUNNING-IN ("Breaking-in")
For long life and peak performance, please observe the
following running-in procedure:
Install the engine and fit the propeller that you propose to
use for flying your model. For example, if you use the pro-
peller indicated in the separate instructions sheet, start the
engine and run it for about 10 seconds with the needle-
valve set for 6,000/6,500 r.p.m., then open the needle-
valve to reduce speed to approximately 4,000 r.p.m. and
run for 20 seconds at this cooler setting. Keep the throttle
fully open, using only the needle-valve to reduce speed.
Repeat this procedure, alternately running the engine fast
and slow with the needle-valve, but gradually extending the
short period of high speed running until a total of approxi-
matelylO minutes running time has been accumulated. For
those who do not have a tachometer, the exhaust gas
colour can be a help: i.e., as the needle-valve is screwed in,
the dense grey exhaust smoke will become less visible.
Following the initial break-in of 10 minutes on the ground,
run-in for a further period in the air. For the first flights,
have the needle-valve set as rich as possible, consistent with
adequate take-off power and, if necessary, readjust the
throttle trim on the transmitter so that the engine does not
stop when the throttle is fully closed.
With each successive flight, close the needle-valve slightly,
until, at the end of 10 flights, the needle-valve is set for
maximum power. The carburettor can now be adjusted for
optimum throttle performance following the advice given in
the separate instructions sheet.
VALVE CLEARANCE ADJUSTMENT
Refer to the INSTRUCTIONS FOR USE OF VALVE
ADJUSTING TOOL KIT sheet contained in the Valve
Adjusting Tool Kit supplied with the engine.
EXHAUST PIPE ADJUSTMENT
The direction of the exhaust pipe may be altered in ac-
cordance with individual installation requirements. The
angle is easily adjusted by loosening the nut that secures the
exhaust pipe to the cylinder head. Use the appropriate
spanner supplied. If longer exhaust pipes are required
for the "Super-Gemini" 240/300 models, use the flexible
exhaust pipes of 12 cm, 17 cm, 24 cm or 33 cm length
which are available as optional extra parts.
LUBRICATION
All the parts of your engine are automatically lubricated by
the oil content of the fuel mixture. The crankcase breather
hole is in the bottom of the timing case and is fitted with a
brass nipple. Fit a length of silicone tubing of approx.
2.5 — 3 mm I.D. to this nipple to conduct away the small
amount of oil that escapes through the breather, (see photo
2).
CARE OF YOUR "GEMINI SERIES" ENGINE
Your engine should be treated with the utmost care at all
times.
-12-