Adjusting Carburetor - Bosch PB-650 Service Manual

20

4-3 Adjusting carburetor

(B)
2K470
FUEL SYSTEM
GENERAL ADJUSTMENT RULES:
Before starting the unit for adjustment, check the
following items:
- Air filter must be cleaned and properly installed.
- Exhaust port of muffler must be clear of carbon.
- The unit must be equipped with blowing pipes.
REQUIRED TOOLS:
- Screwdriver
- Electronic digital tachometer
1. Turn out idle speed screw (A) counterclockwise
until its tip just touches throttle plate (B). Then turn
it in clockwise 1 and 1/2 (one and half) turns.
2. Start engine and warm-up at idle more than three
minutes.
3. Turn idle speed screw (A) to set engine speed to
2,200 to 2,800 rpm on the tachometer.
4. Check that Engine speed at full throttle opera-
tion (WOT) is more than aprrox. 7,000 rpm on the
tachometer.
5. If carburetor can not be adjusted correctly as
(A)
above, check carburetor assembly (Refer to "4-9
Checking diaphragm and others").
PB-650
PB-750