FujiFilm BT-86 User manual

SPECIFICATIONS
Displacement: 5.2cu. in. (86cc)
Horsepower: 7.5HP / 9000rpm
Ignition Style: CDI Automatic
Ignition Timing
R.P.M.: 1100 – 9000rpm
Fuel: 40:1 Mixed Gasoline
Weight: 5.8 lb. (2.6kg)
w/o Muffler
FEATURES
Manufactured by FUJI IMVAC INC.
YOKOHAMA, 235-0005 JAPAN
Worldwide Distributor (except Japan): Hobbico, INC.
Champaign, IL 61826 USA
www.fujiengines.com
Entire Contents © Copyright 2001 FJIZ8600 for FJIG0086 V1.1
The BT-86 engine features an electron-
ic ignition system. This system gradu-
ally delays the ignition timing according
to the number of ignition pulses,
increasing with the engine speed. The
fuel mixture is ignited at almost top
dead center when idling and the timing
is gradually increased as the revolu-
tions increase.
Decompression Valves
The valves are located in the center part
of each cylinder. Pressing this valve
(one or both) before starting will
decrease compression at starting. The
valve on the firewall side may be operat-
ed by a servo for easier operation.
Always use the valves when using an
electric starter. The valves are closed
automatically as the engine fires. For
restarting, press the decompression
valves again to open them.
Operator's Manual for BT-86
™

BEFORE OPERATION
1. Check to see that all screws and bolts are tight. Check carefully for any
cracked, broken or missing parts. Tighten or replace before proceeding.
2. Do not operate engine in a closed room or where ventilation is not adequate.
3. Check to see that there are no foreign objects in the path of the propeller.
Secure any loose articles of clothing so they cannot be drawn into
the propeller.
4. Prepare only the amount of gasoline needed. Aged gasoline could dam-
age the engine and cause it to overheat.
5. Mix gasoline with 2 cycle oil only in the ratio of 40 parts gasoline to 1 part oil
(break-in ratio is 25 to 1.) Using fuel with an incorrect fuel/oil ratio or with oil
not intended for 2 cycle engines could cause damage and allow the engine
to overheat. Use an appropriate fuel filter to eliminate foreign matter.
6. Always allow engine to cool prior to refueling.
Break-in Operation
Operate engine for about one hour with a fuel mixture that contains
a 25:1 fuel/oil ratio. Do not break in by opening the high-speed nee-
dle on the carburetor. Carbon will accumulate in the spark plug,
which will make ignition difficult. (There is no problem if break-in is
done by flying the engine.)
STARTING PROCEDURES
Manual Starting:
1. Make sure the ignition is OFF. Close the choke plate on the carburetor
and open the throttle slightly from the idle position.
2. Rotate the propeller slowly about 10 to 20 times (more in Winter) until fuel
begins to move to the carburetor. (Swing the prop one-half turn to move the
piston from top dead center to bottom dead center, and then back to top dead
center repeatedly. Opposite rotation can also prime the carburetor.)
3. Turn the ignition ON and flip the propeller several times briskly.
4. Turn the choke lever to the OPEN position after you hear an initial firing
and the engine stops. You can squirt gasoline directly into the carburetor
if the engine does not fire.

5. Rapidly flip the propeller until the engine starts. If the engine does not
start, repeat the steps 1-4.
6. After starting, let the engine idle for two to three minutes. Open and close
the throttle until the engine runs smoothly at idle and at full throttle.
Acceleration should also be smooth.
Safety Warnings:
For manual starting, make sure the propeller is properly adjusted on
the propeller shaft to allow you to rotate the flywheel past the ignition
coil at the highest possible speed during starting. Flip the prop rap-
idly from the point where you can first feel the compression.
Warning: Gasoline is volatile and flammable. Gasoline should be
stored in an approved container, away from heat or open flames. Do
not smoke near gasoline. Use caution when transporting gasoline
and take precautions when fueling your engine.
Starting With Optional Spring Starter (FJIG1086)
1. With the ignition OFF, close the choke plate on the carburetor and open
the throttle slightly from the idle position.
2. Rotate the propeller slowly about 10 to 20 times (more in Winter) until fuel
begins to move to the carburetor. (Swing the prop one-half turn to move the
piston from top dead center to bottom dead center, and then back to top dead
center repeatedly. Opposite rotation can also prime the carburetor but will not
be possible when using the spring starter.)
3. Turn the ignition ON. Hold the propeller, turn it clockwise 360° (one rota-
tion) and let it go.Turn the choke lever to the OPEN position after you hear
an initial firing and the engine stops. You can squirt gasoline directly into
the carburetor if the engine does not fire.Repeat steps 1,2, & 3 above, as
necessary.
Starting With Optional Electric Starter (Onboard type or External type)
1. With the ignition OFF, close the choke plate on the carburetor and open
the throttle slightly from the idle position.
2. Turn the propeller with the starter for a few seconds until fuel begins to
move to the carburetor.
3. Turn the ignition ON. Turn the propeller with the starter.
4. Turn the choke lever to the OPEN position after you hear an initial firing and
the engine stops. You can squirt gasoline directly into the carburetor if the
engine does not fire.Again, turn the propeller with the electric starter.

Starting Without Using the Choke (Recommended after the engine is well
broken-in.) Temperature: 60°F (15°C) or higher.
1. Set the throttle at idle.
2. Turn the ignition OFF.
3. Slowly turn the propeller by hand about 20 times (depending on
the temperature).
4. Turn the ignition ON and rapidly flip the prop several times.(Repeat steps
1-3 above if the engine will not start.)
If the engine still does not start, check for the following:
1. Flooding: Rotate the propeller rapidly with the throttle fully opened.
2. If the engine is dry, you can put 5 to 6 drops of fuel directly into the car-
buretor opening.
If you can’t tell whether the engine is flooded or dry, you can check by
the following method:
1. Remove the spark plug. If the plug is wet with gasoline, the engine is
flooded. Let the engine rest a few minutes, replace the spark plug and try
starting again.
2. If the spark plug is dry, put 3 to 4 drops of fuel directly into the cylinder.
Replace the plug and try starting again.
Ignition problems:
Remove the spark plug, but leave the ignition lead connected. Let the base
of the plug contact the cylinder head. Rotate rapidly and check for a spark.
The engine must turn at 500 rpm or more. Try it in dark room. A dirty plug
will not spark. If there is no spark, replace or clean the plug. If the gap
between the electrode and the center post is too large, there will be no
spark. The gap should be about 0.030”. Use a commercial spark plug gap-
ping tool to check this.
We recommend that you use an electric starter until you get used to how this
engine handles.

INSPECTION & ADJUSTMENT
Idle adjustment:
1. Always adjust idle with the engine shut off. Make sure the ignition is OFF.
2. Turn the idle adjust screw counter-clockwise to lower the idle RPM. Turn
the screw clockwise to increase the idle RPM. Turn the screw about 45°
each time. (A too-low idle RPM causes the engine to stall.)
3. A dirty plug makes it difficult to adjust the idle RPM.
High and low-speed needle adjustment:
1. Always make high and low speed needle adjustments with the engine
shut off. Make sure the ignition is OFF.
2. Adjust the needle marked ‘H’ for high speed RPM. Adjust the needle
marked ‘L’ for low speed RPM.To lean the mixture, turn the needle clock-
wise. To richen the mixture, turn the needle counterclockwise.
Normal high and low-speed settings:
It is rarely necessary to change the needle settings. Normally, only the ‘H’ nee-
dle will need adjustment from time to time, and only by a small amount. If the
needles need to be reset, first close them by turning them gently clockwise until
they stop. DO NOT tighten them. Just turn them until they stop.
H:Turn the needle counter-clockwise 1-1/4 turns (±1/4 turn in Winter)
L:Turn the needle counter-clockwise 1-3/4 turns (±1/4 turn in Winter)
The full-throttle mixture is adjusted with the H screw.
If the ‘H’ needle is too lean, it may cause the following three symptoms.
1. Engine stops at full throttle.
2. Engine hesitates when accelerated rapidly.
3. The engine will not come up to full RPM at full throttle.

If the‘H’needle is too rich, it may cause insufficient RPM at full throttle. This
causes carbon buildup on the spark plug.
If the ‘L’needle is too lean, it may cause the following three symptoms:
1. The engine hesitates when accelerated rapidly.
2. The RPM increases at idling.
3. The engine stops when the throttle is moved from high to low.
If the ‘L’needle is too rich, the idle may be unstable.
The position of the ‘H’ needle will vary according to air temperature and
field elevation.
Spark plug:
The recommended plug to use is a Champion RCJ-6Y or 7Y. To avoid
improper operation or possible engine damage, do not use other types of
spark plugs. The plug gap is 0.025”-.030”. If the plug gap is incorrect, adjust
it with a spark plug gapping tool, wash it with gasoline, and allow it to dry
well before you reinstall the plug in the engine. If the plug has become car-
bon-fouled, clean it with a spark plug brush, check the gap, clean it with
gasoline, allow it to dry, and reinstall it.
Propeller:
Always use a well-balanced propeller.
Recommended propellers and their approximate RPM:
Bolly Carbon 24 x 10 (7500rpm)
Bolly Carbon 18 x 12 (6800rpm)
RPM will vary according to temperature, atmospheric pressure, humidity, etc.
Test conditions:
·Temperature 10C (50F)
·Humidity 40%
·New engine with 90 minutes break-in running
·No cowling, but with plastic spinner
·40:1 standard gasoline/oil mixture

SAFETY WARNINGS
Always use lightweight spinner for ease in balancing. Using a thick metal
spinner could cause the propeller shaft to break.
Do not use silicone fuel line because it will be attacked by the fuel. Use vinyl
or neoprene rubber fuel line. Make sure the fuel line is well-secured to the
metal tubes of the fuel tank so it won’t come off in flight.
Keep the fuel line away from the cylinder head, especially in a cowling. The
engine’s heat can damage the fuel line.
After transporting your model, remove the air from the fuel line between the
tank and the carburetor. The fuel line diagram shown above makes it easy
to let the air out.
Drain fuel from A.
Always use oil intended for 2-cycle engines.
Use heat-resistant rubber or silicon hose to extend the exhaust outlet from the
muffler. Metal tubing may cause the muffler retaining screws to loosen or cause
damage to the cylinder. Muffler pressure to the fuel tank is not required.
If the engine will not be used for more than a month, drain the fuel tank, and
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 car-
buretor over an extended time will damage the diaphragm valve, and clog
passages inside the carburetor.
Break-in: Do not adjust the ‘H’ screw. This engine should not be broken in the
same way you would a glow engine. That would cause carbon to foul
the plug and damage your engine.
The proper fuel/oil mixture ratio is 25:1.

Because the carburetor is more complicated than those used in glow engines,
keep the fuel clean by using a fuel filter. Use a filter intended to be used with
gasoline engines. 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 your stor-
age container.
The shaft on the rear of the engine is used with an optional spring starter or an
optional electric starter.
If the choke valve, in operation, touches the corner of the carburetor, bend the
choke valve so it will operate freely.
The included engine mount is manufactured to be light in weight for model air-
planes. Use a stronger engine mount if the engine is used on a test bench, or for
any use other than on a model airplane. Do not use the included engine mount
with anything other than model airplane.
Kill Switch
Your engine must have a kill switch installed. This is for practical as well as safety rea-
sons. Your model will not comply with the AMA Safety Code unless it has a kill switch
installed. We recommend the Great Planes™Manufacturing Gas Engine Ignition Kill
Switch (GPMG2150).
Stopping the Engine
You can stop your engine by adjusting the idle stop screw to allow the carburetor
to close past the normal idle position. This will choke the engine and it will quit.
3-Year Limited Warranty
For USA and Canada
Fuji Engines warrants this product to be free from defects in materials and workmanship for a period of three (3) years from
the date of purchase. During that period, Fuji Engines will, at its option repair or replace without service charge any prod-
uct deemed defective due to those causes.You will be required to provide proof of purchase date (receipt or invoice).
This warranty does not cover damage caused by crash, abuse, misuse, alteration or accident. Damage caused by
customer disassembly, tampering, use of substandard fuel, use of incorrect accessories (spark plug, prop, etc.) or
any use of the engine for which it is not specifically intended will automatically void the warranty of the engine.If there
is damage resulting from these causes within the stated warranty period, Fuji Engines will, at its option, repair or
replace it for a service charge not greater than 50% of the current retail list price. Be sure to include your daytime
telephone number and e-mail address in case we need to contact you about your repair.
Under no circumstances will the purchaser be entitled to consequential or incidental damages.This warranty gives
you specific legal rights, and you may also have other rights, which vary from state to state.
If you attempt to disassemble or repair this unit yourself, it may void the warranty.
For service on your Fuji Engines product, either in or out of warranty, send it post paid and insured to:
Hobby Services
1610 Interstate Drive
Champaign, Il 61822 U.S.A.
[phone]
www.hobbyservices.com
Along with your engine and proof of purchase date, please include a complete written explanation detailing the prob-
lem(s). State your name and address clearly. For repairs not covered under warranty, you must specify whether you
wish the charges to be billed COD or if you wish to be notified of the charges so you can send a check.
Outside USA and Canada, contact
local importer for warranty information. Printed in USA