Adjusting Carburettor - Echo PB-655 Service Data

8

2-3 Adjusting carburettor

(F)
SERVICE INFORMATION
1. Start engine and warm it up alternating engine
(E)
speed between WOT and idle every 10 seconds for
1 minute.
2. Adjust idle mixture needle with 2.5 mm blade
screwdriver (E) to reach maximum engine speed
just before drop off.
3. Set idle speed to 2,800 r/min by turning idle adjust
screw. Engine speed ranges 2,800 +/- 30 r/min after
idle adjust screw adjustment.
4. Turn idle mixture needle anticlockwise to reduce
idle speed 200 to 300 r/min in the range of 2,500 to
2,600 r/min.
NOTE : Engine speed must be allowed to stabilize
a minimum of 20 seconds after each adjustment of
L mixture needle to assure accurate tachometer
readings.
5. Adjust hi speed (H) mixture needle and obtain
maximum WOT engine speed just before lean drop
off using 2.5mm blade screwdriver.
6. Turn hi speed (H) mixture needle anticlockwise
to reduce WOT engine speed 10-20 r/min. Minimum
WOT engine speed after adjusting should be over
6,800 r/min.
7. Start engine, and verify engine idle speed ranges
from 2,400 to 2,800 r/min, and WOT engine speed
ranges from 6,800 to 7,300 r/min. When final
adjustment is completed, the engine should idle,
accelerate smoothly, and attain WOT per above
(C)
specification.
8. After adjusting carburettor, insert and secure new
plug(s) (F) A259-000000 deep in the needle holes
per the Emission Directive using limiter plug tool (C).
NOTE : Engine WOT, and idle speed r/min in field
operation may vary from final adjustment
specifications due to changing ambient conditions,
fuel, and engine loads. Safe engine rpm variances
should be within the WOT, Idle speed ranges listed
in Section 1-1, otherwise the carburetor should be
readjusted.
PB-655
PB-755