STARTING PREPARATIONS
GLOW PLUGS PREPARATIONS
Use a Standard long (K&B #7311 included installed in your
engine) glow plug when using less than 25% nitro or High Per-
formance (K&B #7300) glow plug when using more than 25%
nitro. You also need a 1.5 volt battery to operate the glow plug.
FUEL SPECIFICATIONS
Use a good commercial grade two cycle glow fuel (K&B 500 or
K&B 1000) with 15%~25% nitro-methane (more nitro helps in
cold weather).
BREAK-IN FORMULA: 20% oil, 15% nitro-methane, and the
balance methanol.
AFTER BREAK-IN: The nitro-methane percentage may be in-
creased to 25% or higher desired. LOW QUALITY FUELS CAN
RUIN THE ENGINE IN A SHORT PERIOD OF TIME. Never use
fuel with less than 18% oil content by volume.
Be sure the fuel contains the right percentage of oil (18-22%
by volume) and the fuel oil content is at least a 50-50 mix of
castor oil. Not all synthetic oil. Use only fuel that lists percent-
ages on the label by volume.
Keep fuel clean and filter it during fueling. Keep exposure to air
to a minimum as methanol will absorb moisture rapidly.
MARINE PROPELLERS
A Prather 215 SS or 220 SS (Stainless Steel) propeller is rec-
ommended as a starting size for this engine.
Be sure prop is balanced. Vibrations are usually caused by
props and excessive wear or breakage of the prop shaft may
occur.
These propellers as well as a prop balancer may be purchased
form your local hobby store or direct from K&B.
Use of smaller propellers can cause vibrations and damage to
stops, the needle valve setting is too lean. Unscrew the needle
1 more turn and try again. If engine starts, runs slowly and
briefly the mixture is too rich. Turn the main needle in 1/2 turn
and restart. IF THE ENGINE DOES NOT FIRE AT ALL, refer to
the TROUBLE SHOOTING section in this text.
If you launch the boat and the engine dies after only 10 to 20
feet, the engine is usually running too lean.
Now adjust the main needle as described in STARTING AND
BREAK IN above. ALL ADJUSTMENTS MUST BE DONE AF-
TER RUNNING THE BOAT IN THE WATER. Adjusting without
running the boat in the water will not provide the correct set-
tings. The engine must have the load of the prop in the water to
obtain the correct settings.
ADJUSTING THE R/C CARBURETOR
1. Start the engine, launch the boat and open the carburetor to
the full open position, then bring the boat to shore adjust the
main needle and relaunch the boat. Repeat this until peak
R.P.M. is reached. Then back out the main needle slightly to
keep the engine on the rich side of the setting.
2. Close the carburetor barrel slowly until the lowest possible
speed is reached without the engine stopping. Set your trans-
mitter trim to this setting at full up so the engine can be killed
by moving the trim level to full down position.
the engine. Too large a propeller can
cause excessive wear as the en-
gine is lugged below its designed
operating R.P.M. range.
PRESSURE LINE HOOK UP
Muffler pressure should be con-
nected to the tank from the nipple
in the center of the muffler.
CARBURETOR SET UP
K&B engines are fitted with a vari-
able mixture carburetor which automatically alters both fuel
and air mixtures as it’s closed. Best and most reliable carbu-
retor settings are obtained after engine break-in.
The carburetor on the 3.5 has a preset idle mixture and a high
speed mixture needle.
High Speed Needle Valve Adjustment: The needle, located
on the carburetor assembly, controls all the fuel supply to the
engine at the maximum throttle setting. It does not control the
fuel at lower throttle settings.
As a starting point for the High Speed Needle adjustment, close
the needle valve (clockwise) all the way closed, DO NOT force
it, then open it (counterclockwise) 5 to 6 turns. This setting is
an average and will require further adjustments.
3. LOW SPEED and MID-RANGE ADJUSTMENT are fixed and
no adjustment can be made. carburetor.
ACTUAL STARTING
NOTE: The engine runs in a clockwise direction
when looking directly down at the flywheel.
This is
opposite from an aircraft or car engine so the electric starter
may have to be connected to your 12 volt battery in reverse.
WITHOUT battery connected, open the carburetor barrel to
wide open position. Open the high speed needle valve as pre-
viously described. Choke the engine by placing your finger over
the carburetor air inlet and slowly turn the flywheel over three
times clockwise. You should see fuel being drawn up the fuel
line. If fuel is not drawn into the carburetor, open the main
needle one more turn. Fuel should be drawn into carburetor.
Close the barrel to about the 1/3 open position and connect
the 1.5 volt battery to the glow plug, start the engine with your
electric starter. Once the engine starts, open the carburetor to
1/2 throttle briefly and close it back to 1/4 throttle. If the
engine responds well launch the boat in to the water. Running
of the engine outside the water must be kept to a minimum.
If it slows, dies or only starts with a brief bust of power and
Throttle always
closes to idle
counter-clockwise
on the 3.5 carb
open
