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CS-400
CARBURETOR ADJUSTMENT
Engine Break-In
New engines must be operated a minimum duration
of two tanks of fuel break-in before carburetor adjust-
ments can be made. During the break-in period your
engine performance will increase and exhaust emis-
sions will stabilize. Idle speed can be adjusted as
required.
High Altitude Operation
This engine has been factory adjusted to maintain sat-
isfactory starting, emission, and durability performance
up to 1,100 feet above sea level (ASL) (96.0 kPa). To
maintain proper engine operation and emission compli-
ance above 1,100 feet ASL the carburetor may need to
be adjusted by an authorized ECHO service dealer.
IMPORTANT
If the engine is adjusted for operation above
1,100 feet ASL, the carburetor must be re-
adjusted when operating the engine below 1,100
feet ASL, otherwise severe engine damage may
result
1. Before adjusting carburetor clean or replace air lter
and mufer “Spark Arrestor Screen”.
2. Make sure the bar and chain are properly adjusted.
3. Start engine and run several minutes to bring to
operating temperature. Flash choke twice during
warm-up to clear any air from the fuel system.
4. Stop engine.
Turn “H” speed needle counterclockwise (CCW) to
stop. Turn “L” speed needle midway between full
clockwise (CW) stop and CCW stop.
5. Idle Speed Adjustment:
• Start engine, turn “Idle” speed adjustment screw
CW until the saw chain begins to turn, then
turn screw out CCW until the saw chain stops
turning. Turn screw out, CCW, an additional 1/4
turn.
Idle adjusting screw
Low speed needle (L) High speed needle (H)
6. Accelerate to full throttle for 2 - 3 seconds to
clear any excess fuel in the engine, then return
to idle. Accelerate engine to full throttle to
check for smooth transition from idle to high
speed. If engine hesitates turn “L” needle CCW
1/8 turn and repeat acceleration. Continue
adjustment until smooth acceleration results.
7. Check idle speed and reset if necessary as
described in item 5. If a tachometer is available
idle speed should be set to 2400 - 2900 r/min.
WARNING
Cutting attachment must not move when unit
is idling.
CAUTION
When starting, idling adjustment speed
should be adjusted not to rotate the saw
chain. Correct idle speed is adjusted 2400 to
2900 r/min. Or 1/4 turn CCW from the point
the chain stops moving.
When you experience trouble with the
carburetor, contact your dealer.