Originally posted by CAP232CM
As for breaking in the motor. Usually you run it at full throttle for 5 or 6 tank fulls then your ok to fly. You want to turn out the high speed needle about 2 1/2 to 3 turns don't worry about the low end at this time. You want to hear the engine switching from clean 2 stroke to rich 4 stroke kind of like how a weed eater sounds when it's running. Run the engine for about 5 minutes then let it cool and repeat untill you have run at least 5 tanks through it.
Darenm, you did not say what kind of engine you have so I'll assume it's the traditional ABC type.
If thats the case you should NOT 4-stroke the engine during break in. This was necessary when pistons and cylinders were steel with little or no taper. With the new design engines power output is much higher as is the amount of heat produced, this extra heat, combined with the newer materials used, causes the upper cylinder and head to expand more than the remainder of the engine. To compensate for this a greater amount of taper is machined into the cylinder, this sometimes causes a noticeable tight spot at the top of the stroke. When in 4-stroke mode there is not sufficient heat generated to cause the proper expansion and may result in piston/cylinder scoring. You should run several tanks of fuel at a rich 2-stroke mode allowing cool down between tanks. place a couple of drops of after run oil in the carb and flip by hand with the glow driver disconnected to insure good lubrication during start-up. Open the throttle about 1/8 and attach the glow driver and use the electric starter.If the engine is too tight at the top for your starter heat the head with a covering heat gun to expand it a little, that usually does the trick.
