ABC motor break-in is just a little different then a ringed motor.
One it usually takes only ½ hour or less to break in the motor. Also ABC motors need to be run a little liener while breaking
in. Always read the owners manual for breaking in your motor. I can not stress this enough. There is a link to
Engine Manuals at the end of this article.
High Speed Needle.Turn the high speed needle valve in (usually clockwise)
till it stops. Do this lightly!! Even using medium force while closing the needle can damage it. With the needle now in the
closed possession, open it 3 to 4 turns. (3 usually works)
Fuel the tank and apply power to the glow plug.
Starting. Use an electric starter or chicken stick to flip the prop
Initial Adjustments When the motor starts, let it warm up for
about 30 seconds then remove the glow plug. If the motor quits after power to glow plug is removed. Turn the high speed needle
in (leaner) a ¼ turn and restart motor. Repeat this operation till motor will stay running with out the glow plug at full
throttle. The engine may be running rough at this time. This is normal! The motor is running in 4 stroke mode.
Finer Adjustments. Slowly turn the needle in (leaner usually
clockwise) and listen for the muffle sound to change. The pitch of the muffler will grow higher with as you turn it in. At
a certain point the pitch will change abruptly getting much higher, stop here and move the needle out (richer, usually counter
clockwise) a few click. You will notice the motor changing form a higher cleaner pitch sound to a lower pitch rougher sound.
When this point is found then lean the motor just enough that it runs at the higher pitch sound. Let the motor run like this
for 5 minutes.
Pinch and Release Testing. After 5 minutes, pinch the fuel line
releasing it quickly. If the motor speeds up, turn the needle in a quarter turn and let the motor run for 5 more minutes.
If it does not speed up, DO NOT TURN the needle in more. Let the motor run for another 5 minutes., then pinch the line again
and see if the motor speeds up again repeat this procedure. If at any time the motor starts to lose power when turning the
needle in (called sagging), automatically turn the needle out (opposite direction ) a quarter turn. Allowing your motor to
run when it sages can damage it severely.
After about 1 ½ tanks have been run through the motor, make smaller adjustments (1/8 turns) to the needle. Somewhere from
here to about 3 or 4 tanks the motor will not increase in rpm when you pinch the line. Some motors will take more or less
tanks to reach this point depending on the make and model of engine you have or if the motor was pre-run at the manufacture.
The motor is almost broken in fully, and the high speed needle almost perfectly set.
Hold Up Test. Here is a simple test to check the setting of your high
speed needle. You should do when your first going to fly your plane or after any adjustments are made. After starting your
engine, go to full throttle and hold your plane with the motor pointing straight up towards the sky. If the motor sages and
starts to lose power, STOP immediately and richen your high speed needle a ¼ turn. If the motor speeds up a little and continues
to run strong, your motor is SET!!!!!
Throttle Transition. If your motor will transition form high to low
throttle smoothly or with little trouble, then the low end needle will not need to be adjusted at this time. The motor will
continue to break-in slightly when you fly through the next gallon of gas and small clicks of adjustments may be needed here
and there. If your motor gurgles and spits a lot when going from low to high throttle, the low end needle will need to be
adjusted. Go to the section on adjusting your low end needle.
Congratulations!!! Your motor is broken in.