Breaking in your new engine.

When you buy a new engine you will need to break it in first. This is done because it will net have much power straight out of the box. It will also overheat if you do not break it in correctly. If done correctly it will extend the life of your engine. The secrete is to let it burn a little rich.  Overheating will eventually ruin your engine.

 

With your engine on a test stand or mounted inside of the plane, fuel it up. Connect the fuel tubing from the fuel output to the carburetor  (I recommend using an inline filter between the fuel tank and the carburetor). The other fuel line is connected from the muffler to the fuel  tank (the pressure from the muffler pressurizes the fuel tank and helps get the fuel to the engine).

 

Open the needle valve on the carburetor about 3 turns. The fine fuel adjustment on the other side may not need adjusting (this one is the one with the screwdriver slot in it).

 

Now upon the throttle wide open and place your finger on the opening of the carburetor and give the prop three flips counterclockwise (this primes the fuel tubing).

 

If your model is not on a test stand make sure that someone is holding your model.

 

Close the throttle until it is open.

 

Connect the glow plug connector.

 

Its time to start your engine. Use a chicken stick to flip the prop counterclockwise. After a few flips hopefully your engine will start.  If it does not start and it is getting harder to flip the prop STOP. You flooded the engine. If you continue to try to start it you can ruin  your engine (It becomes hydrolocked). If your engine becomes flooded disconnect the glow plug clip and unscrew the glow plug.  Turn your engine upside-down and give the prop a few clockwise flips to clear out the fuel. Reconnect the glow plug and clip and turn the needle valve a ¬ turn to clockwise (this leans out the engine). Flip the prop counterclockwise with the chicken stick.

 

Once that the engine is started you will need to burn at least 2 tanks of fuel. During the first tank gradually increase the throttle.  Do not run it on full throttle for more then about 2 seconds (it could cause it to overheat). The engine will make a lot of smoke and  will sputter and backfire. That is normal. If the engine dies restart it. After you burned one tank, refuel and start your engine. Open  the Throttle wide open. Pinch the fuel tubing that goes to the carburetor two or three times. The engine should speed up. Slowly  turn the needle valve clockwise until the engine does not speed up anymore then turn it back « turn (turning it back keeps the engine from overheating).

 

Your engine should be broken in enough to fly. As your engine is being broken in, turn the needle valve clockwise a little at a time until it as about ¬ turn from the maximum prop speed (because it leans out in the air and if it is too lean it will overheat).

 

It will take about 1 gallon of fuel until your engine is broken in.

(From the Bay Aron Model Airplance Club  website)