Echo CS-271T Service Manual page 32

30
4-7 Adjusting carburetor (continued)
4-7-3 Adjusting carburetor
Idle adjust screw
L mixture needle H mixture needle
4. Turn L mixture needle CCW reducing engine idle speed 700 rpm to set idle speed at 2,900 rpm. The
idle speed range is 2,800 - 3,000 rpm.
5. Set idle speed to 3,200 rpm by turning Idle adjust screw. Engine rpm should be stable at 3,200 +/- 50
rpm after idle adjust screw adjustment.
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.
6. Before adjustment, WOT engine speed should be less than or equal to 11,400 rpm. If rpm is higher,
turn H mixture needle CCW until 11,400 rpm is achieved. To make the final WOT engine speed adjust-
ment, turn the H mixture needle CW in 1/8 turn increments with the engine at idle. After each adjustment,
accelerate to WOT, and check rpm. The final rpm should fall within 11,600 - 11,800 rpm.
C
IMPORTANT : The limiter caps must be properly installed on L and H mixture needles to comply
with Emission Regulations.
8. Start engine, and verify engine idle speed ranges from 2,900 to 3,500 rpm, and WOT engine speed
ranges from 11,300 to 12,500 rpm. Make sure the chain does not rotate when engine is idling. When final
adjustment is completed, the engine should idle, accelerate smoothly, and attain WOT per above specifi-
cations.
FUEL SYSTEM
1. Start and warm engine for 100 seconds alter-
nating engine speed between WOT and idle every
5 seconds. Turn H mixture needle CCW until en-
gine speed drops to approx. 11,400 rpm at WOT.
NOTE : Do not run engine at high speed without
load longer than 10 seconds, or engine damage
may occur.
2. Adjust L mixture needle using 2.5mm blade
screwdriver to reach maximum engine rpm just be-
fore lean rpm drop off.
3. Set idle speed to 3,600 rpm by turning Idle
adjust screw. Engine rpm should be stable at 3,600
+/- 50 rpm after idle adjust screw adjustment.
7. After adjusting carburetor, screw new limiter
cap CCW on the limiter cap removal tool (C) (P/N
89801) approx. 2 turns as shown. Align the limiter
cap tabs (A) with locating slots (B) in extended
housing of carburetor and put the limiter caps on L
and H mixture needles respectively. Gently press
the caps onto L and H mixture needles (do not
rock caps back and forth). Remove tool (C) then
fully seat caps until flush with housing of carbure-
tor using bar tool.
CS-271T
B
A
A
B