Part No. 5680
SPECIFICATIONS
Size
.28
Bore
0.725
Stroke
0.68
HP
0.625
Max RPM
13,000
Weight (oz)
10.5
Propeller
9 x 6
 

WARNING

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!

 
ENGINE BREAK-IN

It is unnecessary to give the engine a prolonged break-in. However, we suggest that you mount your engine to a break-in stand to familiarize yourself with it and with the carburetor operation. It is strongly recommended that fuels containing more than 15% nitro-methane be avoided until after the engine has been in operation for about an hour on a mild fuel and under mixture-rich conditions. Mixture-rich operation is when the engine has a slight "burbling"sound and probably a very smoky exhaust. This helps lubrication and cooling when the engine is new.

Typically, an engine will be ready for full-throttle and mixture-lean operation after less than an hour of running. When the engine holds RPM after the mixture has been leaned out ... when RPM's don't sag after a moment or so ... the engine can be considered to be broken-in.

 
ENGINE and FUEL TANK INSTALLATION

The engine may be installed upright, on either side, or inverted (upside down). The 1/4-inch diameter output shaft mounts standard hole-size propellers.

Mount the engine firmly to hardwood rails, or to the firewall, if you use a radial 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. It should be located close to the engine. 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.

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STARTING THE ENGINE

With a full tank of fuel, the recommended propeller installed, and a fully charged booster battery of no more than 1.5 volts ready for connection to glow plug, proceed as follows to manually start an engine installed in a plane.

1. With the booster battery disconnected, turn the needle valve counter-clockwise 2-1/2 turns from the fully closed position. 2. With the booster battery STILL disconnected and with the throttle wide open, place finger tip over the carburetor inlet and flip the propeller quickly 2 or 3 times, to prime the engine. 3. Remove finger tip from the carburetor inlet then close the throttle to a fast idle setting and again flip the propeller quickly 2 or 3 times. 4. Connect the booster batter clip to the glow plug. 5. Slowly turn the propeller (counterclockwise) and "feel" for a momentary resistance - which indicates ignition of the mixture in the cylinder. 6. Quickly flip the propeller to start the engine and, then disconnect the booster battery after the engine has started. 7. Except for the first hour or so, as noted under "Engine Break-in", adjust the needle valve by turning clockwise to lean the mixture for full power operation. If the RPM starts to sag (back-off) you have leaned the mixture too much and you should then turn the needle valve counterclockwise until the RPM picks up and holds steady.

STOPPING THE ENGINE: If you wish to stop the engine while on the ground, bring the engine down to low idle and pull or pinch the fuel line off to run the engine dry.

 
PROPELLERS
A 9" x 4"p propeller is recommended as a starting size. However, experimenting with one pitch or diameter larger or smaller can improve results for your particular airplane.
 
GLOW PLUG
This engine comes equipped with a standard Long Reach Glow Plug (K&B PN 7311). Performance will vary, depending on the glow plug and fuel used.
 
ENGINE CARE

Dust and dirt are the worst enemies of your engines. At all times, keep the engine and the fuel clean. Wipe engine surfaces clean with a rag dipped in a solvent such as methanol or pain thinner, or use a soft- bristle, metal brush to clean engine surfaces.

If it becomes necessary to disassemble and clean the engine, remove only the cylinder head and the back- plate from the crankcase. Submerse the engine in solvent while turning crankshaft by hand, and use a soft- bristle brush to clean inside engine. Flush engine repeatedly to assure removal of any solid particles. Be sure that the transfer and exhaust ports in the cylinder wall are uncovered by the piston.

If the carburetor is to be removed for cleaning, or to enable better cleaning of the engine, disconnect the throttle linkage and then loosen the draw bar at the base of the carburetor. Lift out the carburetor, taking care not to lose the O-ring seal. Disassemble and clean the carburetor using a solvent such as methanol. Blow out all the passage ways. When reinstalling the carburetor, press it gently downward against the O-ring seal while tightening the draw bar.

 
CARBURETOR OPERATING INSTRUCTIONS

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 full close. IMPORTANT: THE BARREL MUST CLOSE IN A CLOCKWISE ROTATION. The opening in the barrel spray bar faces the crankshaft.

 
NEEDLE VALVE ADJUSTMENTS

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. WARNING: DO NOT RUN THE ENGINE AT A "LEAN" SETTING.

2. LOW-SPEED and MIDRANGE 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. 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 counterclockwise to richen the mixture.

 
NEEDLE VALVE ADJUSTMENTS - GENERAL
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.
 

RECOMMENDED FUEL

K&B 505 (5% nitro) or K&B 510 (10% nitro)
 

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