Use and Care Manual

25
CS-490
CARBURETOR ADJUSTMENT
Every unit is run at the factory and the carburetor is
set in compliance with Emission Regulations.
In addition, the carburetor is equipped with high
speed and low speed needle adjustment limiters
that prevent settings outside acceptable limits.
1. Before adjusting carburetor clean or replace air
filter and muffler “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. Idle Speed Adjustment:
• Start engine, turn “Idle” speed adjustment
screw clockwise until the saw chain begins
to turn, then turn screw out counterclockwise
until the saw chain stops turning.
Turn screw out, counterclockwise, an
additional ¼ turn.
WARNING
Cutting attachment must not move when unit
is idling.
5. 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.
6. Check idle speed and reset if necessary as
described in item 4.
If a tachometer is available idle speed should be
set to 2800 r/min.
CAUTION
When starting, idling adjustment speed
should be adjusted not to rotate the saw
chain.
Correct idle speed is adjusted 2800 r/min.
Or ¼ turn counterclockwise from the point
the chain stops moving.
When you experience trouble with the
carburetor, contact your dealer.
Idle adjusting screw
High Altitude Operation
This engine has been factory adjusted to maintain
satisfactory starting, emission, and durability
performance up to 330 m above sea level (ASL) (96.0
kPa).
To maintain proper engine operation and emission
compliance above 330 m ASL the carburetor
may need to be adjusted by an authorized ECHO
service dealer.
IMPORTANT
If the engine is adjusted for operation above
330 m ASL, the carburetor must be readjusted
when operating the engine below 330 m ASL,
otherwise severe engine damage may result.