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RC Model Airplane Gas Engines

RC Model Airplane Gas Engines

OK, so you’ve installed your gasoline engine properly, and made sure that the fuel tank is properly installed and the fuel lines and fuel filter are all hooked up correctly, but you still can’t get any fire in the hole—the engine just won’t start. As a safety note here, we always recommend using a properly sized heavy duty starter like those from Sullivan Products. If however, you are starting your engine by hand, be sure to have a friend help and hold the tail of your airplane secure so the plane won’t move forward when the engine does fire up.

What else can you do?

1. Well, the first thing is to check that the prop blade is positioned in relation to the magneto magnets or the electronic ignition’s triggering magnet as indicated in your engine’s operating manual. Sometimes a small adjustment in blade positioning will make all the difference.

2. I like to start my engines using my left hand and set the prop so that the blade is at 11 o’clock and I swing it to the 7 o’clock position. This directs the force downward instead of upward. The magneto fires the spark plug at about the 9:30.

3. If your engine starts, burns off the prime then quickly dies, this indicates a fuel draw issue. Check your fuel lines for any kinks, blockage or pin holes.

4. Also check your tank for proper internal setup. Sometimes, the fuel tank can be installed upside down, and won’t draw fuel properly. When you flip the prop with the choke closed, it should draw fuel. You can see it moving toward the carburetor in the fuel lines.

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RC Model Airplane Gas Engines

5.  If the carburetor won’t draw any fuel, check to make sure the needle valves are open.

6. Also, make sure the carburetor is tightly fastened in place and that the small hole and passage feeding pulse pressure from the engine case to the carburetor isn’t blocked.

7. Check the fuel intake screen filter and make sure it is clean. This screen is located under the carburetor’s top cap (the one held in place with a single screw). If it’s dirty, carefully remove it and flush it with fresh gas until it is clean, or replace it.

8. Check that the engine head/cylinder case is tightly fastened to the engine case and that the gasket is undamaged. Even a small air leak here can prevent the engine from starting.

9. If there’s no spark, make sure the kill switch is in the correct (Run) position. With electronic ignitions, make sure the battery is fully charged and the wiring to the timing sensor is properly connected.

10. If your engine loses compression, check for a stuck or broken piston ring. If this happens suddenly during flight, don’t turn the engine over by hand, as this could score or gouge the sleeve. Carefully disassemble the engine and check for internal damage. If you don’t want to do it, send the engine in for inspection and repair.

11. To ensure proper operation of your gasoline engine, always use clean, well filtered fuel. Use a filter in your fuel supply container, as well as between your engine and fuel tank. If you use a T-fitting in the engine supply line for filling and defueling your model, place the filter between the carburetor and the T Fitting.


Once set up properly and adjusted, gasoline engines are very user-friendly, start easily and provide excellent fuel economy. Once the carburetor is set, it won’t usually have to be adjusted for most if not all of the flying season.

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Add a Comment
  1. Big safety issue in your photo. I have seen it time after time. Neck strap and other items around the neck. If that gets pulled into the prop it will not be pretty. I have a habit of putting my strap down my shirt when starting planes.

    1. Charles, great point! A glove would also be a good idea.

    2. Great safety heads up Charles Brooks. Sometimes the obvious is overlooked.

    3. I agree, nothing loose or dangling near any props, gas,glow, or electric.


  2. I do not see a glove on the fellow in the picture starting the engine. A safety issue.

    Also, a bystander standing in front of the engine. Another safety issue.

  3. Great review Gary works fineon my gas engines

  4. You left out the rubber tipped vaccum do dad under the 4 screws.

    This thing sticks w/a new engine. Take it out and clean it so

    your carb will draw fuel.


  5. Wow!!!! you start with your left swinging the prop??? that is ackward

  6. Is that a finger in tho photo of the carb????ugh!!!!!

  7. What could be used in stead of nitro in a glow plugs engine

  8. Rough crowd. Article is well written. Thanks for posting.

  9. I second Charles Brooks comment. Put the strap down your shirt or take it off your neck.

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