The K&B .45 DF is a high performance engine, designed especially for ducted fan models. 
It is an improved version of our previous, highly successful engine, known throughout
the world for its power and proven reliability, and will provide countless hours of sport or
competition performance if properly handled and maintained.

This engine also features a drum rotor induction system.  The drum rotor is made of steel,
then hardened and ground to a super smooth finish.  It runs in a bronze bushing,
which gives the unit exceptionally long life.


Displacement .45 cu. in. (7.41cc)
Bore .870 (22.1mm)
Stroke .760 (19.3mm)
R.P.M.  2,000 - 25,000
Power Output 2.2 HP @ 25,000
Weight 13.4 Oz. (380g)


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!



GLOW PLUGS: This engine is designed to use our long reach glow plug (K&B Part No. 7311).

FUEL: We recommend either K&B 500 (12-1/2% nitro) or K&B 1000+ (25% nitro) fuel.  K&B 500 will give your engine more economy, and longer life.  K&B 1000+ will give your engine more power, less economy, and less life.

A pressurized fuel system must be used to boost the fuel to the needle valve.  Install a pressure fitting on the tunes pipe, just behind the apex where the cones join.  The recommended tuned pipe is the Mac's product No. 1260 (8.5cc) muffled pipe.  Direct a length of fuel line from the pressure fitting vent on the fuel tank.  In turn, the fuel pickup line goes to the needle valve.

  • Never place your hand in front of the fan for any reason while the engine is running.
  • Keep rags, articles of loose clothing, or anything that might be ingested, well clear of the duct intake.
  • Always start the engine at an idle throttle setting.
  • Wear eye and ear protection.
  • If your fan installation calls for 6-32 screws for mounting the engine, drill out the mounting lug holes with a No. 28 drill bit.  Cover the front bearing exhaust, and carburetor openings, and drill the lugs from the bottom.  Be sure to blow or brush away all aluminum chips and dust.

MAKE PERIODIC CHECKS. After every flight, remove the glow plug and check the oil condition.  If it is broken or badly distorted, replace it.  The glow plug life will be longer when you achieve a good needle valve setting.

After every four flights, check tightness of the engine head and mounting screw, as well as fan and spinner security.

After every twelve flights, check the tuned pipe coupler, and tightness of the clamps.


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) inches in total length.


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:


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 "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.  After adjusting the mixture, remember to "lock" it into position by tightening the bottom screw.
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.
All series “94” carburetors must run with exhaust pressure from the tuned pipe connected to the fuel tank.

© Model Engine Corporation of America, All rights reserved.
K&B and the oval logo are Registered Trademarks of Model Engine Corp. of America
Registered U.S. Patent Office

No part may be reproduced without written permission from
MECOA/K&B -- P.O. Box 5 -- Sierra Madre, CA 91025 U.S.A.