Welcome to the family of K&B Engines, the name synonymous with performance
and quality for over 50 years.

To assure complete satisfaction with your newly purchase engine,
please read the instructions carefully and follow the
steps of proper installation, operation, and care.

.40 cu. in. (6.44cc)
.840 (21.3mm)
.720 (18.3mm)
 2,200 - 24,000
Power Output
2 HP @ 24,000
12.8 Oz. (.37kg)
Propeller P-235
Part No. 4075


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!



Due to the nature and design features of the "ABC" type engine, the piston and sleeve have been set up 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.  It's 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 slightly rich needle valve setting for the first two runs.  These runs should be made for periods of no less than five (5) minutes each.  Typically, an engine will be ready for continuous full throttle and a steady needle valve setting after ten (10) to fifteen (15) minutes.
Mount the engine firmly to your motor mount.   For maximum security, use carbon steel, self-locking hex nuts and hardened alloy steel machine screws to mount the engine.  The fuel tank size, location, and height have a great influence on engine operation.  For carburetor engines, locate the tank so that its horizontal centerline is from 1/4" to 3/8" below the fuel connection to the carburetor.
This engine is designed to use the long reach glow plug (K&B P/N 7311) or the HP glow plug (K&B P/N 7300) for performance fuels.
We recommend using K&B 1000+ (25% nitro) or K&B Speed Fuel (50% nitro).


Please consult your hull manufacturer for the best propeller for your application.

If you are unfamiliar with this line of carburetors or are a new modeler,
please do not attempt to start the engine until you have read and
understand the following instructions:

1.   NEEDLE VALVE SET-UP - Locate an area to install the remote needle valve assembly.  This assembly must be in the fuel line between the tank and the carburetor.  The line should not exceed five (5) inches in total length.

2.   LINKAGE SETUP - Notice the barrel will rotate 360 degrees.   Using your radio and trim functions, set the barrel movement for full open and close.  IMPORTANT: THE BARREL MUST BE CLOSE IN A CLOCKWISE ROTATION.  The opening in the barrel spraybar faces the crankshaft.


Note that there are two fuel metering adjustments:

1.    HIGH-SPEED NEEDLE VALVE - This needle valve, located on the remote Needle Valve Assembly, controls all the fuel that comes to the engine, whether the engine is running at high, mid-range, or idle speeds.  It does not affect the low speed rich/lean setting.  The High Speed Needle Valve's main function, however, is to meter the high speed fuel mixture.

2.    LOW SPEED and MID-RANGE MIXTURE ADJUSTMENT - The rich/lean adjustment is controlled by the "slotted" screw located on the side of the carburetor where the low speed disk is housed.  The rich/lean mixture control is set at the factory and may require only a "fine" adjustment for your application.  WARNING: DO NOT RUN THE ENGINE AT A "LEAN" SETTING.  To adjust the mixture, loosen the bottom screw (do not remove) and adjust the top slotted screw.  This screw only turns 1/4 turn to either the right or left of center.  It does not turn all the way around.  Turn the screw clockwise to "lean" the engine and counter-clockwise to "richen" the mixture.


As a starting point for the high-speed needle adjustment, completely close the needle valve (clockwise), then open it (counter-clockwise) three and a half turns. This setting is an average and may require further adjustments. For higher altitudes (3,000 - 4,000 feet), close needle valve approximately 1/2 turn.


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MECOA/K&B -- P.O. Box 5 -- Sierra Madre, CA 91025 U.S.A.