Displacement .452 Cu. In. (7.41cc)
Bore .870 (22.1mm)
Stroke .760 (19.3mm)
R.P.M. 2,000 - 25,000
Power Output 2.75 HP @ 25,000
Weight 1 Lb. 14 Oz. (.85Kg)
Propeller P-230


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!


NEW CLEANING AND LUBRICATING FEATURES: A cleaning hole has been added to the front plate to aid in cleaning the front or top bearing. Simply place an aerosol can of Liquid Wrench (or similar product) up to the hole and “back” flush the bearing. Continue to flush the bearing until you see fresh cleaner come out under the flywheel. The bearing may also be oiled in the same manner.

A lubricating hole for the flex shaft has been added to the lower unit. It is recommend that each time, before you run the unit, you lubricate the cable with a mixture of 50% STP and 50% 20-50 weight oil. K&B still recommends that you continue to remove, inspect and re-lube the flex cable (using Lube P/N 8449) on a continued basis.

AIR COOLED HEAD: A feature of this engine is the air cooled head. This feature does not mean that the engine is to be run outside of water for prolonged periods of time as the lower unit does require water for cooling. CAUTION: Air cooled head becomes hot after usage.

HEAD CLEARANCE: Your engine has been factory set with a head clearance of approximately .010 to .015.

MUFFLER INSTALLATION: Two 4-40 x 3/8” screws are included within your accessory package for muffler installation. Simply slide the muffler through the cutout in the lower unit and install the screws and gasket through the muffler adaptor in the matching holes on the muffler. Tighten screws.

MAINTENANCE: We recommend after each days running, that you check each bolt and screw for tightness.

CAUTION: For maximum life of propeller shaft bushing do not operate engine out of the water for a period of longer than thirty (30) to forty-five (45) seconds.

THE LOWER END: Tests have proven that the cable drive is far superior to the gear drive. Maintenance is cut down to a minimum. However, we ask that you occasionally check and lubricate the flex cable. Check for excess wear and fraying. Do not rotate the engine by flipping the propeller in a counter-clockwise direction. Fraying and unwinding may occur. We recommend a good silicone base lubricant such as K&B marine grease (P/N 8449) for your outboard as well as other drive units.

GLOW PLUG: This Engine is designed to use the long reach glow plug (K&B P/N 7311). For high nitro fuels use K&B 7300 Glow Plug.

FUEL: We recommend using K&B 525 (25% nitro) or K&B Speed Fuel 550 (50% nitro).

BREAK-IN: An “ABC” type engine, (Aluminum, Brass, Chrome) does not require prolonged break-in periods. However, we 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 on the boat and running in the water for periods of not less than five (5) minutes each. Typically, an engine will be ready for continuous full throttle and a leaner needle valve setting after ten (10) to fifteen (15) minutes of running.

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.

3. The crankshaft may seize inside the front plate and fracture.

The engine runs in a clockwise rotation. Make certain that your starter motor is running in the same direction. With the tank full of fuel, radio on and glow plug battery leads off, fully open the carburetor, and with your finger covering the carburetor venturi, spin the engine with the starter for about a two second burst. This primes the engine. Now close the carburetor to the starting position. Connect the GLOW battery and spin the engine again. The engine should fire up and run. We recommend that you start your engine close to the water so that you will not have too far to walk with the engine running. It is also advised that you keep the engine at a slow or not greater than a slightly fast idle until you get into the water, as over revving plus overheating can damage your engine.


We recommend that you use a fuel filter in your fuel system. Install the fuel filter on the fuel pickup tubing between the tank and carburetor. It will keep foreign matter from going into the carburetor to create clogging. However, the filter also can clog up. Therefore, should it clog, remove the filter from the fuel line and clean it as per the manufacturer’s instructions.

PROPELLERS: Propellers are naturally an important factor. Most propellers that are available on the market need balancing and “cleaning up”. Unbalanced props cause cracks on boat hulls, not to mention robbing your engine of horse power and your boat of performance. So, balancing the prop is very important.

“Cleaning up” the propeller means to sharpen the leading edges of the blades and generally sanding, smoothing and polishing the entire prop.



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:


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) niches in total length.


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

Note that there are two fuel metering adjustments:


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.


The rich/lean adjustment is controlled by the brass low speed disk located on the side of the carburetor. Using the allen wrench provided turn the disc clockwise to “lean” the mixture and counter clockwise to “richen” the mixture. 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.
As a starting point for the high speed needle adjustment, completely close the needle valve (clockwise), then open it (counterclockwise) 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.


All series “94” carburetors must run with exhaust pressure from the exhaust system to the fuel tank.

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