Echo cs-520 Instruction Manual - Carburetor Adjustment
23
CS-520
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.
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 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.
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 2,900 - 3,100 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 2,900 to
3,100 r/min. Or 1/4 turn CCW from the point
the chain stops moving.
When you experience trouble with the
carburetor, contact your dealer.
Idle adjusting screw
High speed needle (H)
Low speed needle (L)