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© 08/2013 ECHO Inc.
MAINTENANCE CS-303T
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 “H” (High Speed) and “L” (Low
Speed) needle adjustment limiters that prevent settings
outside acceptable limits.
Engine Break-In
New engines must be operated a minimum duration of two
tanks of fuel break-in before carburetor adjustments can be
made. During the break-in period your engine performance
will increase and exhaust emissions will stabilize. Idle speed can be adjusted as required.
High Altitude Operation
This engine has been factory adjusted to maintain satisfactory starting, emission, and durability
performance up to 1,100 feet above sea level (ASL) (96.0 kPa). To maintain proper engine operation and
emission compliance above 1,100 feet ASL the carburetor
may need to be adjusted by an authorized ECHO
service dealer.
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 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. 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 “T” CW until the saw chain begins to move, then turn
screw out CCW until the saw chain stops moving. Turn screw out, CCW, an additional 1/4 turn.
When carburetor adjustment is completed, the saw chain should not move at idle, otherwise
serious personal injury may result.
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 value listed on technical data page.
When starting, idling adjustment speed should be adjusted to prevent the saw chain from moving.
When you experience trouble with the carburetor, contact your dealer.
T
L
H