Instructions / Assembly

MAINTENANCE CS-400

38 X7503255900

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

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.