Echo CS-2511T Instruction Manual - page 27

25

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. 

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 ½ turn. 

   WARNING

Cutting attachment must not move when unit 

is idling. 

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 3000 r/min. 

   CAUTION

When starting, idling adjustment speed 

should be adjusted not to rotate the saw 

chain.  

Correct idle speed is adjusted 3000 r/min.  

Or ½ turn CCW from the point the chain 

stops moving.  

When you experience trouble with the 

carburetor, contact your dealer.

Idle adjusting screw

Low speed needle (L)

High speed needle (H)

High Altitude Operation

This engine has been factory adjusted to maintain 

satisfactory starting, emission, and durability 

performance up to 1100 feet above sea level (ASL) 

(96.0 kPa).  

To maintain proper engine operation and emission 

compliance above 1100 feet ASL the carburetor 

may need to be adjusted by an authorized ECHO 

service dealer. 

IMPORTANT

If the engine is adjusted for operation above 

1100 feet ASL, the carburetor must be 

readjusted when operating the engine below 

1100 feet ASL, otherwise severe engine damage 

may result.