Echo PB-602 Operator's Manual page 20

20
Initial Adjustment
1. With engine off, turn HI speed screw (C) counterclockwise to
stop.
2. Turn LO speed screw (B) midway between stops.
3. Turn idle screw (A) until tip of screw just touches throttle plate;
then turn three (3) turns clockwise.
Final Adjustment
IMPORTANT
Limiter caps prevent exceeding C.A.R.B. and E.P.A. emission
limits and over rich adjustment, but not over lean adjustment,
which can cause engine failure: Do not exceed recommended HI
speed engine R.P.M. during operation, or for long periods during
adjustment.
1. Start engine, run at idle for one minute.
2. Complete warm up by running at full throttle for 5 minutes,
operating choke twice to clear air from carburetor chambers.
3. Run at idle and accelerate to check for smooth transition from idle
to high speed; if engine hesitates, turn LO speed screw (B)
counterclockwise 1/8th of a turn at a time until acceleration is
smooth.
4. Use a tachometer to adjust idle speed to specifications found on
page 9.