How To Break In an RC Engine

Nitro car enthusiasts want to know the best way to break in RC engines and there is no shortage of opinions on this subject. Although there is no single best way to break in an RC engine, many methods can do more damage than good. The steps outlined in this article have produced great results time and time again.

Things You'll Need

• 15 to 20 percent RC car fuel
• Air filter lube
• After-run oil or WD-40
• Glow plug igniter
• Rags
• Car stand or brick
• Old cardboard box

Instructions

Pre-break-in procedures

1. Lube the air filter. Apply the lubricant sparingly; an air filter with too much lube will restrict airflow and cause the engine to stall. The best method--and probably the least messy--is to apply a few drops of lube in a sandwich bag and then toss the air filter element into the bag. Work the lube into the element and then reinstall the element on the carburetor.

2. Remove the glow plug and apply a few drops of after-run oil down the opening. Spin the flywheel to distribute the lube. This will lubricate the engine's vital components and make the engine easier to start. If you do not have after-run oil, WD-40 works well, too.

3. Make sure that your glow igniter has fresh batteries or it is completely charged. Make sure the batteries in your radio and in the vehicle's battery holder are fresh, too. Run the vehicle without the body installed to provide maximum airflow to the engine.

Static break-in

1. Fill the tank with fuel and prime the carb by yanking on the pull-start rope until the fuel travels down the fuel line and enters the carb. If you have a starter box by all means use it because it will save you a lot of effort by not having to yank on the pull-start rope.

2. Install the glow igniter on the glow plug and start the engine. If the engine starts up momentarily and then stalls, raise the idle by turning the idle-speed screw clockwise a quarter turn. Once the engine starts, place the vehicle on a stand to raise the tires off the ground. If you do not have a car stand, a brick or even a shoe box will work satisfactory. Place a cardboard box next to the tip of the muffler to collect the unburned fuel and oil that will spit out of the pipe. This tip will prevent staining your driveway. You do not need to have your radio on at this point so save your batteries until you complete the next few steps.

3. Allow the engine to burn through the first tank of fuel with the vehicle stationary on the stand. If the wheels start to spin the engine is developing enough RPM to engage the clutch. Lower the idle a bit by turning the idle-speed screw counterclockwise until the wheels stop spinning. When the fuel in the tank is almost depleted, squeeze the fuel line to stop the flow of fuel to the carb and the engine will stall. Let the engine cool down for a few minutes.

4. Refill the tank with fuel, and lean the air/fuel mixture by turning the high-speed needle-valve clockwise 1/8 turn. Start the engine and follow the procedures in steps 2 and 3 while the engine consumes the second tank of fuel.

Street break-in

1. After the engine has cooled down for a few minutes, close the high-speed needle-valve another 1/8 turn. Fill the tank up with fuel and turn on the radio and power up the vehicle. The next few steps will require running the vehicle on the street. Use good judgment; do not run the vehicle on a busy street or an area with a lot of people.

2. Start the engine and run the vehicle at half throttle for three-second bursts. Physically count out three seconds; (one-thousand-one, one-thousand-two, and one-thousand-three) and then stop the vehicle for three seconds. Stopping the vehicle and waiting three seconds will allow the carburetor to load up with fuel, which will keep the engine well lubed. Repeat this process until the engine runs through the tank of fuel. It is best not to let the fuel in the tank empty completely. Stop the engine when a small amount of fuel is still left in the tank.

3. Fill up the tank once again, and close the high-speed needle-valve another 1/8 turn. Repeat the procedures outlined in steps 5 and 6 for the next four tanks of fuel. As the engine starts to break in, you'll probably notice that the idle speed will increase gradually. This is normal because every time you lean out the air/fuel mixture the engine will idle faster. Lower the idle by turning the idle-speed screw counterclockwise.

4. After the engine has consumed six to eight tanks of fuel, it will be sufficiently broken-in. You can now tune the engine for maximum performance. Engine tuning is a subject for another article, so read the tuning instructions that came with your engine to help you get started.