FUJI-IMVAC BT-24 Operator’s Manual
Operator’s Manual for BT-24
SPECIFICATIONS
Displacement: 1.46 cu in [24cc]
Horsepower: 2.2 hp @ 10,000 rpm
Ignition Style: CDI Automatic
Timing Module
RPM: 1,200 – 9,500 rpm
Fuel: Gas/2-cycle engine oil
Weight w/Muffler: 3.4lb [1.55 kg]
Fuji-Imvac is not related to the original Fuji Engines sold by Mecoa.
Manufactured by FUJI-IMVAC INC.
YOKOHAMA, 235-0005 JAPAN
Worldwide Distributor (except Japan): Hobbico, Inc.
Champaign, IL 61826 USA
www.fuji-imvac.com
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SAFETY TIPS AND WARNINGS
Always use a balanced spinner and a balanced prop. An unbalanced spinner
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and prop combination will cause high levels of vibration and may cause the
propeller shaft to break.
Always use a lightweight spinner on your engine. Lightweight spinners are
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considered to be those with a cone wall of 1mm or less. Heavy spinners could
cause the propeller shaft to break.
Securely tighten the spinner and prop on the engine to prevent it from being
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thrown off the engine while running.
Never use a prop that has hit the ground. Even though it may look good from
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the outside, it may be cracked on the inside which may cause it to disintegrate
while in use. Do not use a nicked, cracked or split propeller.
Keep foreign objects away from the propeller. Make sure that nothing can be
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“sucked in” by the propeller. Never start the engine on loose gravel or sand.
Keep onlookers away from the running engine, especially small children.
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FJIZ0024 for FJIG0024 V2
Do not attempt to stop the engine by throwing anything into the path of the propeller.
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Make sure the fuel line is well-secured to the engine and to the fuel tank so that
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it won’t come off in flight.
Do not use silicone fuel line because it will be attacked by the fuel. Use vinyl or
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neoprene rubber fuel line.
Always secure the fuel line away from the cylinder head. The engine’s heat can
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damage the fuel line.
Never touch the engine after a run. The engine will be hot and it may burn you.
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Before transporting your model, remove all the fuel from the fuel tank and fuel lines.
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Always use high-quality oil intended for 2-stroke engines.
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Use only low-octane, alcohol-free gasoline. The carburetor diaphragm will
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gradually deteriorate if you use gasoline with alcohol (ethanol, gasohol, etc.).
You will need to replace the diaphragm in about 80 hours of operation if you use
gasoline with alcohol.
Muffler pressure to the fuel tank is not required.
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Do not install your throttle servo or kill switch servo inside the engine compartment.
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Doing so could cause radio interference. Install all electronic radio devices at least
305mm [12"] away from the engine. The throttle pushrod should be non-metallic.
If the engine is not to be used for more than a month, drain the fuel tank and
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remove any fuel from inside the carburetor. Do this by running the engine at idle
until it quits by running out of fuel. Keeping gasoline inside the carburetor over
an extended period of time will damage the diaphragm valve and clog passages
inside the carburetor.
Because the carburetor is more complicated than those used in glow engines,
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keep the fuel clean by using a fuel filter. Use a filter intended to be used with
gasoline engines. Metal filters intended for glow engines are too coarse and will
not screen out finer particles. Always filter your fuel by using an appropriate filter
before putting it into the airplane’s fuel tank.
If you intend to run this engine on an engine stand, or on any other rigid mount,
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use rubber mounts. The crankcase and other parts of the engine may crack if
you do not provide some kind of vibration absorption mechanism. A rubber
mount is not necessary if the engine is mounted on a model airplane.
Do not operate the engine in a closed room or where ventilation is not adequate.
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Gasoline is extremely flammable. Keep it away from an open flame, excessive
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heat or sources of sparks. Do not smoke near the engine or the fuel tank.
This engine was designed for use in a model aircraft. Do not attempt to use it
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for any other purpose.
Always install a kill switch that can be operated both manually and with the R/C
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transmitter.
PARTS LIST
BT-24 Engine w/Muffler
Propeller Flange with Propeller Washer
Propeller Bolt
Friction Ring
(4) 5mm x 12mm SHCS with Lock
Washers and Flat Washers
(4) 5mm x 22mm SHCS with Lock
Washers and Flat Washers
Spark Plug Wrench
4mm Allen Wrench
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FEATURES
CDI (Capacitive Discharge Ignition) for simple operation.
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An optional Digital Tachometer (FJIP9920) is available to monitor rpm and
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ignition battery voltage.
SPARK PLUG
The recommended spark plug is a Champion RCJ-6Y or 7Y. To avoid improper
operation or possible engine damage, do not use any other type of spark plugs.
The plug gap should be 0.4mm to 0.6mm [0.016" to 0.024"]. If the plug gap is
incorrect, adjust it with a spark plug gapping tool, wash it with gasoline and allow
it to dry completely before you reinstall the plug in the engine.
Note: If you want to check if the spark plug works, remove the spark plug from
the engine, connect it to the coil and make sure the metallic threaded end of the
spark plug touches the engine. Spin the propeller rapidly through top dead center
and check for a spark. This procedure only works in a dark room as there is too
much light outside to see the spark.
The various spark plug manufacturers have much information on their web sites
regarding spark plug performance and health. For more information, check:
http://www.championsparkplugs.com/sparkplug411.asp
PROPELLER
Always use a well-balanced, high-quality propeller.
The recommended propellers are:
High Performance Wood Prop: 16" x 10"
18" x 8"
Carbon Prop: 16" x 10"
OIL
Fuji-Imvac has developed a special oil, Super Lube Oil (FJIP9910 – 250cc), to work
with their engines. This oil is of extremely high quality and it has exceptional
lubricating properties. This oil can be mixed with gasoline at much higher ratios than
other engine oils which allows the engine to develop more horsepower and last
longer. It is recommended that you use Fuji-Imvac oil with all your Fuji-Imvac
engines. Break-in procedures are slightly different than those when using standard
oils. Please refer to the table below for oil contents. Fuji-Imvac Oil is available from
your Fuji-Imvac distributor or hobby shop.
Break-in (Stage 1): 1 gallon of gasoline with 50:1 (2%) oil content ratio.
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Break-in (Stage 2): 1 gallon of gasoline with 100:1 (1%) oil content.
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Normal running: In un-cowled or well-cooled installations 150:1 (0.65%) oil
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content.
In-cowl or poorly cooled installations 100:1 (1%) oil content.
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Do not try to use these engine oil ratios with any other brand of oil other than
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the Fuji-Imvac oil.
Do not use the Fuji-Imvac oil with any other brand of engines.
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If you have been running the engine on other oil and wish to switch to Fuji-Imvac
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oil, follow the break-in procedure for Fuji-Imvac Engines oil.
If Fuji-Imvac oil is not available, or if you prefer to use a different brand of oil, use
the standard fuel/oil ratios as shown below. Never experiment with cheap oil or
with obscure brand names. Be certain to select only high-quality oil that is
intended for use in gasoline R/C model airplane engines.
Break-in: 1 gallon of gasoline with 25:1 (4%) oil content.
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Normal running: 40:1 (2.5%) oil content.
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PREPARE THE ENGINE
1. Check to see that all screws and bolts are tight. Check carefully for any cracks,
broken or missing parts. Tighten or replace before proceeding.
2. Install the prop shaft on the flywheel using two
5mm x 22mm [3/16" x 7/8"] SHCS with lock washers
and flat washers. Use thread-locking compound on
the screws.
3. Connect a kill switch to the ignition control module. It is recommended to
install a manual switch and a servo-operated switch. This can be accomplished
using two receiver ON/OFF switches.
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INSTALLING THE FUJI-IMVAC BT-24 ON YOUR AIRPLANE
Note: The Fuji-Imvac BT-24 must be installed on a 9mm [3/8"] lite-ply firewall or on
a 6.4mm [1/4"] birch ply firewall. The firewall must be securely glued to the airplane.
Use triangle stock and pin the firewall with hardwood dowels to reinforce the firewall
glue joints. Never install the Fuji-Imvac BT-24 onto a firewall thinner than specified
because it may fail due to the power of the engine.
1. Use the supplied mounting template (on the back cover of this manual) to drill the
engine mounting bolt holes and the necessary clearance hole on the firewall.
2. Install the engine on the firewall using four 6.4mm x 19mm or [10-24" x 3/4"]
socket head cap screws, four #10 flat or lock washers and four #10 blind nuts. Use
some thread-locking compound, such as Great Planes® Pro™ Threadlocker.
3. Install a manual and radio-operated kill switch (GPMG2150). Install a kill
switch servo at least 305mm [12"] away from the engine.
4. Install the throttle servo at least 305mm [12"] away from the engine. Make sure
that you get the carburetor’s full range of rotation with your servo travel.
5. Install the ignition module securely in the airplane forward area. It is
recommended that a thin piece of foam rubber be placed between the module
and the mounting surface and that rubber bands are used to hold the module
in place. 4mm [5/32"] screws and washers can also be used to secure it in
place, but soft mounting the module is always the best choice.
6. Secure all connections with heat-shrink tubing.
7. Cut all necessary clearance and cooling holes in the cowl.
8. Make sure the cowl is secured to the airplane and that the spinner to cowl
clearance is at least 3mm [1/8"].
BREAK IN THE ENGINE
The break-in procedures for your engine will vary depending on the type of
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engine oil you will use. Please refer to the “Oil” section for fuel/oil mixture ratios
and break-in times.
Do not adjust the high-speed needle on the carburetor to break in the engine. If
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you do so, carbon will accumulate in the spark plug and that will make ignition
difficult.
Do not run at full power for extended periods of time while breaking in your
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engine.
Make sure that the engine has adequate cooling. While breaking in, the engine
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may run at slightly higher temperatures.
If you wish to do so, you can break in your Fuji-Imvac BT-24 while flying your
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airplane. Just make sure you observe all recommendations above.
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