We won't cover problems associated with improper operation under warranty.
  The compact silencers and tuned pipe silencers made by HP are tuned to the respective engines. A variety of manifold is available which will fit also to your model.

RUNNING IN PERIOD. Normal glow fuel without nitro-methane, after running-in period glow plug fuel with 5~10% ntiro-methane, maximum power glow plug fuel with 10~25% nitro-methane.

Old or minor quality fuel can corrode metal surfaces and destroys the egnine.

Fuel with synthetic oil tnds to run lean while airborne. A slightly richer setting that that castor blended fuels will prevent leaning out of the engine. Changing viscosities of different fuels may affect the needle settings of the carburetor.


In general, use hot glow plugs if temperatures are low, engine has low compression, and fuel has no nitro-methane.

Use cold glow plugs if temperatures are high, engine has high compression, glow plugs are often damaged, and fuel has high nitro-methane.

Voltage of glow plug battery should not exceed 2V.

Strong vibrations can also damage glow plugs. Mount your engine firmly and balance props.


Propeller should always be balanced properly and must be free of damage.

Spinners, may not press on prop-blades.

  Especially while installed in cars or ground vehicle, use air cleaners to prevent dust and dirt from being sucked into the engine.

Mount the engine firmly and avoid unnecessary vibrations. Aluminum engine mounts or metal mounting beams are to be preferred. The mount bores should be in line with the engine mounting holes. The crankcase could be distorted if the mounting screws are forced into their holes. Make sure that the air intake of the carburetor is unobstructed.

The fuel tank should be as near to the engine as possible, tank centerline to be at spraybar level.

The use of pressurized fuel system is recommended. The necessary pressure is supplied by the silencer - every HP-silencer is fitted with a pressure nipple. The pressure tubing from the highest point of the tank should be short and free of kinks. A fuel filter between tank and carburetor helps to avoid fuel supply problems.

WARNING: Never run your engine without silencer.


Before every starting procedure, you should check without connected glow plug whether the engine turns freely. If not, the engine is flooded and excessive fuel has to be removed.

Screw out the glow plug and turn the prop quickly to throw out excessive fuel.

Screw in glow plug again and start the engine with connected battery.

WARNING: If you apply an electric starter, make sure that the engine is not flooded. Liquids cannot be compressed and will prevent engine from turning. Heavy damages of the piston pin, connecting rod, and crankpin may result. These damages are not covered by warranty.




During the break-in period care should be taken not to overload the engine. The following rules should be observed:

1. Best way to break-in your engine is to fly it. Don't use too large and too heavy models.

2. Breaking-in props should have fine pitch.

3. Use a fuel with a minimum content of 20% castor oil.

4. Make sure that your engine is operating in reasonably clean air. Dust and dirt ingested can ruin your engine quite quickly.

5. During the first few minutes of operation the needle valve must be adjusted to a rich setting, with the engine "four-stroking". Subsequently, the mixture is leaned out the point where the engine just picks up "two stroking". With this setting, the engine is allowed to empty the first tankful of fuel on the ground.

6. With this carburetor setting, proceed to flying the engine (2-3 flights, without vertical maneuvers). When the engine shows signs of leaning out, land the model and re-adjust needle valve. For further flights, the mixture can be leaned out gradually, but yet without adjusting the needle valve for full power.


1. Give the engine time to warm up.

2. At first, the engine is set for maximum RPM with the main needle valve as customary. Then the throttle valve is closed, leaving open a slit of only .5mm approx.

3. Close the throttle valve and reopen it after 3-4 seconds. If the engine picks up slowly only and/or smokes and "coughs", the idle mixture is too rich. To amend, lean out the idle needle valve clockwise by a small increment at a time.

4. If the engine stops abruptly when the throttle valve is opened, the idle mixture is too lean. To amend, turn the idle needle valve anti-clockwise.

The carburetors are supplied factory-adjusted. In case you should alter the basic adjustment by accident, here are a few notes on the basic setting: Using a pressurized fuel tank, unscrew the full-throttle needle about 4 turns (counter-clockwise). Screw in the idle needle until it stops, then unscrew it about 2-1/2 to 3-1/2 turns (counter-clockwise). Screw in the stop screw until the throttle slide remains open by about 1/2-1mm.


The Hirtenberger slide carburetor incorporates a piston-operated injection system, which injects extra fuel into the motor's intake when the throttle is opened rapidly.

The special shape of the throttle slide ensures that the variation in intake cross-section remains constant. This feature makes it possible to adjust the motor's speed precisely over the entire opening range of the carburetor.


The motor should be started with the carburetor at the idle position. The full-throttle setting is adjusted first. Screw in the full-throttle needle clockwise until the motor leans out from a four-stroke to a two-stroke. Only apply full throttle for brief periods, to avoid running the motor too fast. This process of adjusting from "rich" to "lean" should be repeated a number of times in order to find the ideal setting for an even two-stroke. The final setting can only be found by field testing - usually the motor then needs to be set a little "richer".

The carburetor's idle setting can now be adjusted. To do this, close the throttle slide to about 1mm. If the motor stops after a brief rise in running speed, then the idle needle must be unscrewed (counter-clockwise) until the motor continues running evenly when the throttle slide is closed.

If, on the other hand, the motor cuts out after a longish period with the running speed gradually falling, then the idle mixture is too rich, and the idle needle must be screwed in (clockwise) until an even idle is obtained.

If the motor stops running when the throttle slide is opened, then the idle mixture is set too lean. Unscrew the idle needle until the motor accelerates cleanly without hesitation.



Your HP Model Engine has passed rigid factory inspections and is warranted to be free from defects in materials and workmanship for a period of 90 days (read warranty). Retain your sales receipt as the as proof of purchase and date of purchase is required.

This warranty does no apply to damage caused by:

1. Shipping and handling.
2. Improper break-in.
3. Use of fuel other than specified.
Crash, misuse or abnormal service.
5. Use of muffler or tuned pipe not approved by RJL.
6. Any modification, alteration, or abuse of the engine.
7. Use for purposes other than engine was designed.
8. Use of improper type glow plug.
9. Plugging of vent line on bottom of engine.
10. Running engine without adequate cooling.
11. Use of incorrect size propeller.
12. Rusted internal parts.
13. Damage caused by hydraulic lock.

Other exclusions from warranty are marring or scratching of the finish, any incidental or consequential damages caused by, or resulting from, a defect in material or workmanship, and normal wear.

DO NOT DISASSEMBLE YOUR ENGINE! Doing so will void your warranty. No exceptions! Call us first and explain your problem.

Our liability under this warranty is limited to the repair or replacement of the defect or defective part at our factory and does not include inbound shipping expenses. Specifically, no responsibility is assumed for any damage to any model, accessory, radio control equipment, person or property resulting from a crash in which a RJL or HP model engine is used.



Any questions? Call or write: (include your phone number with all correspondence)

PO BOX 5 --- Sierra Madre CA 91025
Tel. 626-359-0016


©2011-1998 Model Engine Corporation of America, All rights reserved.
HP is a Registered Trademark of Model Engine Corp. of America
Registered U.S. Patent Office

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