How to Install a 4 Stroke RC Engine

Written by sarah terry
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A four-stroke engine is generally more expensive than its two-stroke counterpart. Four-stroke engines provide a more realistic sound, however. The four-stroke nitro engine has a lesser gas consumption, which is a plus with nitro fuel at £22 a gallon. Four-stroke motors generally run cleaner with fewer emissions, produce more torque, and allow for the use of a larger propeller and more static thrust. A regular gas four-stroke motor is cheaper to run. You can use a mixture of 20-to-1 to 30-to-1 regular gas and oil mixture, which will be more efficient, clean-running and reliable than the four-stroke nitro engine.

Skill level:
Moderately Challenging

Things you need

  • Model aircraft fuselage
  • 1 standard servo with mounting hardware
  • Servo linkage (to connect to throttle on the engine)
  • 1 complete four-stroke motor with all mounting hardware and muffler
  • Fuel tank
  • Plastic fuel tubing
  • Glow plug starter and charger
  • Radio transmitter
  • Receiver (installed on the aircraft)

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  1. 1

    Choose the type of installation that will best suit you model. You can mount the engine sideways, straight forward or upside down. Different types of mufflers exist to accommodate any way you choose to install the engine. Read the engine manual in its entirety, and review your aeroplane model instruction manual for engine installation.

  2. 2

    Install the engine mount on the firewall, as instructed in the manual. Make sure that you attach the engine mount securely. If you're using bolts and nuts to attach the motor mount, use tread lock on each bolt. If you're using screws, you can dip the screw in epoxy prior to installing it.

  3. 3

    Mount the motor in position temporarily. Check for clearance and placement of the servo control linkage to the throttle. Install the servo and connect it to the receiver, adjusting the length of the linkage to the throttle. Check for proper operation and verify that the servo moves freely.

  4. 4

    Turn on the power on your transmitter and on the aircraft. Check the throttle control and make sure you have a full range of operation over the throttle. Then turn off aircraft battery and transmitter.

  5. 5

    Run the fuel lines to the gas tank. The fuel lines should fit nicely without being squeezed by the cowling. Make sure they are not touching any moving parts of the engine, servos or control linkage. Install according to manufacturer's recommendations.

  6. 6

    Secure the engine permanently to the engine mount using tread lock. Check all connections, fuel lines, all mounting points for the engine and servos a second time. Install the muffler, first oiling the threads and making sure the pressure line is connected properly.

  7. 7

    Pour a few drops of recommended oil on the push rod tubes and the crankcase. This will provide adequate lubrication for the first run on the engine. Fill the fuel tank with factory-recommended fuel for breaking in the engine. Secure the aeroplane so that it won't move while the engine is running.

  8. 8

    With the throttle fully opened, prime the engine by rotating the propeller a few turns counterclockwise. Do not connect the glow starter plug yet. Plug the muffler exhaust to help get the fuel into the carburettor. Turn the propeller slowly a couple of times to make sure the engine is not flooded.

  9. 9

    Turn the prop clockwise up to the compression stroke. Set the throttle to one-quarter open position. Plug the glow starter on the glow plug. Using an electric starter or using a "chicken stick," spin the propeller until the engine starts. Leave the glow starter connected until you have adjusted the high-speed needle valve.

Tips and warnings

  • Before each flight, always check that the engine is securely attached, that all bolts and screws are tight, and that the fuel lines are connected properly. Check for and clear air bubbles in the fuel line prior to take off. Use only fresh fuel.
  • Although the typical break-in period for an engine is about 40 minutes, do not exceed 3,500 to 4,000 RPM for the first 10 to 15 minutes. Read your engine manual on how to further adjust the idle needle valve and proper settings for smooth operation of the engine. After setting the idle properly, adjust the throttle adjustment screw or use the trim set-up on the transmitter.
  • Read the engine manual about the break-in procedure for your engine twice. This is a critical step for proper operation and the long life of the engine. Not following break-in procedures can seriously damage the engine.
  • Proceed with extreme caution when removing the glow plug starter from a running engine, so that you don't put your hand or arm around or on top of the propeller. These engines produce great power and high RPMs and will cause serious injury.

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