Displacement .8155 Cu. In. (13.3cc)
Bore 1.040 (26.42mm)
Stroke .960 (24.38mm)
R.P.M. 2,000 - 23,000
Power Output 4.2 HP @ 23,000
Weight 24.5 Oz. (695g)
Propeller P-250


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!


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:

The carburetor enables easy adjustment of the idle speed, idle mixture and the high speed mixture.

1.    High Speed Needle Valve

Locate an area to install the Remote Needle Valve assembly using the bracket provided. This may typically be attached to the firewall, cowl or rear engine mount lug area. 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.    High Speed Needle Valve Adjustment

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.
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 the needle valve approximately 1/2 turn.

3.   Low Speed and Mid-Range Adjustment

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 counterclockwise 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.
All series “94” carburetors must run with exhaust pressure from the lower unit to the fuel tank.
STARTING THE ENGINE: Because the drive cable is driven from the rear of the engine instead of the front, this engine runs backwards (clockwise) to the conventional engine. For the benefit of those of you that are new to the sport of Model Outboarding, an electric starter motor is required to start this engine. A conventional model airplane starter is normally used. When attaching the starter cords to the battery, make certain that the starter also rotates clockwise. With the tank full of fuel, fuel line attached to the carburetor, radio on and glow plug and washer removed, fully open the carburetor venturi, and with your finger covering the carburetor venturi, spin the engine until fuel sprays out of the glow plug hole. Remove your finger and continue to spin the engine until only a fine spray comes out of the glow plug hole. This primes the engine. Now close the carburetor venturi to the start/idle position, replace the glow plug and washer, connect the glow plug battery wires to the glow plug, and spin the engine again. This time, do not cover the venturi. The engine should fire and run. We recommend that you start your engine close to the waters edge so that you will not have far to walk with the engine running. This minimizes the overheating problems mentioned before.

GLOW PLUG: This engine is designed to use the Long Reach Glow Plug (K&B P/N 7311).

FUEL: We recommend using K&B 1000+, 25% nitro.

HEAD and SLEEVE SHIMS: The head clearance of your engine has been checked and set as close as possible to 18 thousandths of an inch. A shim may have been installed under the head to achieve this. Please replace them should you need to disassemble the engine for any reason.

REMEMBER: Check all bolts on engine and lower unit for tightness after each run.

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 lube such as K&B marine grease (P/N 8449) for your outboard as well as other drive units. Lubricate the shaft generously and often.

IMPORTANT NOTE: The prop shaft assembly and mating part of the lower end casting is threaded (Note: Left-hand Thread) for ease of removal or replacement of the drive cable or prop shaft assembly. Keep this assembly tight at all times.

NOISE REDUCTION: As an option, silicone tubing may be placed between the water outlet on the water jacket and the water fitting in the exhaust cavity to reduce noise levels. If further noise reduction is required, Muffler Plate (P/N 8770) may be added to the lower unit.

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 horsepower and your boat of performance. So, balancing the prop is very important. You can buy a fixture for checking balance or you can make your own. Too make your own, mount two single edge razor blades, sharp edges up, parallel to each other and about 1-1/2 inches apart on a piece of aluminum “U” channel or make your own “U” channel out of wood. Make sure the sharp edges are level with each other and with the table. Slip a length of 3/16 diameter shafting (drill blanks are best) through the prop. Place the shaft across the razor blades with the prop in between. The heavy side of the prop will roll to the bottom. File on this area until the prop is balanced. Do not file on the concave part of the prop.

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


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