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The K&B
.21 DF is an especially high-performance engine designed for
ducted fan models. It is an improved version of our previous,
highly successful engine, known throughout the world for its
power and proven reliability, and will provide countless hours
of sport or competition performance if properly handled and
maintained. |
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SPECIFICATIONS
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Displacement
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.2124
Cu. In. (3.48cc)
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Bore
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.650
(16.51mm)
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Stroke
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.640
(16.26mm)
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R.P.M.
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2,000
- 25,000
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Power
Output
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1.25
HP @ 25,000
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Weight
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9.5
oz
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WARNING
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PLEASE
READ ALL SAFETY
INSTRUCTIONS! Failure to read, understand and follow
these instructions could result in personal injury and/or
property damage to yourself or others.
Take
a few moments to familiarize yourself with the various parts
of the engine. DO NOT DISASSEMBLE YOUR ENGINE! Doing so will
void your warranty. No exceptions!
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ENGINE
OPERATING NOTES
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GLOW
PLUG: This engine is designed to use the Long Reach Glow
Plug (K&B Part No. 7311).
FUEL:
We recommend K&B 515DF (15% nitro, 22% oil by volume).
K&B 515DF will give your engine more economy and longer
life.
BREAK-IN
Due to the nature and design features of the ABC
type engine, the piston and sleeve have been setup to feel
a little tight at the top of the stroke. Once the engine has
been started, the sleeve will pull away from the piston leaving
the exact clearance necessary for maximum performance without
seizing. Its for this reason that an ABC
type engine does not require prolonged break-in periods. However,
we do recommend that you run the engine at a slightly rich
needle valve setting for the first two runs. These runs should
be made with the engine installed in your airplane, or on
a bench test stand, using a 8 x 6p propeller. Typically,
the engine should be ready for continuous full throttle operation
after fifteen (15) or twenty (20) minutes.
TUNED-PIPE:
A pressurized fuel system must be used to boost the fuel to
the needle valve. Install a pressure fitting on the tuned
pipe, just behind the apex where the cones join. The recommended
tuned pipe is the MACs Product No. 1821. Direct a length
of fuel line from the pressure fitting to the vent on the
fuel tank. In turn, the fuel pickup line goes to the needle
valve.
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IMPORTANT
PRECAUTIONS
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- Never
place your hand in front of the fan for any reason while
the engine is running.
- Keep
rags, articles of loose clothing, or anything that might
be ingested, well clear of the duct intake.
- Always
start the engine at an idle throttle setting.
- Wear
eye and ear protection.
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NEEDLE
VALVE ADJUSTMENT
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Assemble
the needle valve onto the carburetor and turn it clockwise
to completely close it. Turn until it wont go any further
but do not force it. Then, turn it counter-clockwise 4 to
4-1/2 turns, if you are running near sea level, 3-1/2 to 4
turns at higher altitudes. As these are only starting settings,
you might have to re-adjust the needle valve to make it the
correct setting for your area. Once you have arrived at a
setting, you can lock the needle valve in place as the carburetor
has a built-in collet lock. Turn the black acorn nut clockwise
to lock the needle valve in place, counter-clockwise to loosen.
It takes a 1/4 inch wrench. Only tighten it enough so that
the needle valve cannot be moved. Do not force it.
CAUTION:
If the engine is run at a lean needle valve setting during
the break-in period, the following may result:
1.
Piston and sleeve will overheat and score.
2.
The connecting rod, crankshaft, and wrist pin will overheat
from lack of lubricant and seize, causing the lower con-rod
bushing to spin in the con-rod, or in extreme cases, the bottom
of the con-rod will break, causing damage to the crankcase,
piston, and sleeve.
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MAINTENANCE
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MAKE
PERIODIC CHECKS. After every flight, remove the glow plug
and check the coil condition. If it is broken or badly distorted,
replace it. The glow plug life will be longer when you achieve
a good needle valve setting.
After
every four flights, check tightness of the engine head and
mounting screws, as well as fan and spinner security.
After
every twelve flights, check the tuned pipe coupler, and tightness
of the clamps.
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TROUBLE
SHOOTING
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If the
engine surges, or goes lean, check the following leaks:
1.
Tuned Pipe Coupler
2. Pressure Line
3. Fuel Tank
4. Engine Front and/or Back Plate
5. Check tightness of Head Bolts
6. Check tightness of Glow Plug
If the
engine wont transition (accelerate from idle to full
throttle cleanly):
1.
Check Pressure Line for leak
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©
Model Engine Corporation of America, All rights reserved.
K&B and the oval logo are Registered Trademarks of Model Engine
Corp. of America
Registered U.S. Patent Office
No
part may be reproduced without written permission from
MECOA/K&B -- P.O. Box 5 -- Sierra Madre, CA 91025 U.S.A.
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