5
After starting and warming the engine for 30–45 seconds, adjust as follows:
Step I-
Move the throttle to 2/3 high throttle position quickly (fast acceleration), then repeat three times. If the engine
accelerates smoothly go to Step III; if acceleration is not smooth go on to Step II.
Step II-
Faulty acceleration and a tendency to quit is usually attributable to a poor fuel mixture in the medium rpm range. Stop
the engine and recheck the fuel feed (the fuel line must not be pinched or broken). Restart the engine and test acceleration
again. If the problem persists, adjust the carburetor. Open the low speed needle by 5 minutes and retest. If acceleration is
smooth, open the needle by another 3–5 minutes—this should be done because the needle was previously set too lean; if
atmospheric conditions changed recently you may have to re-adjust the needle.
If the engine continues not to accelerate properly, open the low speed needle by 10 minutes. If the engine’s operation does not
improve, shut it off and check the basic setting, restart the engine and test the acceleration. If the engine runs correctly, proceed
to Step III.
Step III-
If it continues to not accelerate properly, open the low speed needle by another 10 minutes. If acceleration is faulty, the
defect is likely to lie somewhere other than an adjustment.
Step Iv-
If the engine accelerates correctly, according to the above test, set it at idle speed and accelerate to full speed. Repeat
twice more. If the engine functions correctly, go to Step V. If it cuts out, open the low speed needle by 5–10 minutes more.
If the engine does not respond to acceleration fast enough, keep closing the low speed needle until it starts to cut out in
response to throttle opening. At that point, reopen the low speed needle by 5–10 minutes.
Step v-
If the engine reacts correctly, set it at full speed. If revolutions do not drop, the engine has been adjusted successfully. If
revolutions seem to drop, open the high speed needle by about 5–10 minutes.
caution!
The engine must be stopped while you adjust the carburetor in order to prevent injury by the propeller.
Starting and running a new engine:
Having started the engine, leave it running for about 5 minutes at a higher idle speed. Then run it for about 20 minutes, while
changing revolutions from idle to 1/2–3/4 of the range and shortly holding each position—gradually prolong the holding periods. After
10 minutes of operation, open the throttle to maximum for a period of about one minute. At this point, stop the engine and let it cool
down. Then restart it and check the adjustment. If everything is all right, you can make your first flight. During the first few flights, do
not overload the engine and do not let it run at high revolutions for long periods of time (very important during hot weather). After break
in, fuel and oil should be mixed in the proportion 40:1.