Carburettor Adjustment Procedure; General Adjusting Rules; Presetting Idle Adjust Screw, L Mixture Needle And H Mixture Needle - Echo CS-550 Service Data

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2 CARBURETTOR ADJUSTMENT PROCEDURE

2-1 General adjusting rules

A. Before adjustment, check the following items.
1. The correct spark plug must be clean and properly gapped.
2. The air fi lter element must be clean and properly installed.
3. The muffl er exhaust port must be clear of carbon.
4. The fuel lines, tank vent and fuel fi lter are in good condition and clear of debris.
5. The fuel is fresh ( > 89 octane :
FD" 2-stroke oil.
6. The recommended bar and chain must be installed, and properly tensioned.
NOTE : In order to achieve proper carburettor adjustment, a 38, 40, 45 or 50 cm bar and chain should be
installed on the unit. Otherwise serious engine damage will occur due to overspeeding.
B. Preliminary adjustment. Adjustment by Idle adjust screw of carburettor.
Start and run engine for two minutes alternating engine speed between WOT for 10 seconds and idle
for 10 seconds. Adjust idle speed screw to 2,800 +/- 150 r/min. Make sure WOT engine speed in range
12,500 - 13,500 r/min. If engine does not run correctly after this adjustment, proceed to the next step 2-2.

2-2 Presetting Idle adjust screw, L mixture needle and H mixture needle

SERVICE INFORMATION
) and properly mixed at 50 : 1 with "ISO L-EGD" or "JASO FC/
RON
(D)
(C)
(B)
(A)
Tools Required : Small screwdriver with 2.5 mm
blade, P/N G310-000050 electronic tachometer,
P/N Y089-000090 D-shaped tool (A).
1. Turn L and H mixture needle clockwise until
lightly seated, and then turn out both mixture nee-
dles following turns.
L mixture needle (B) : 1 3/8
H mixture needle (C) : 3 3/8
NOTE : If needles are overtighted during seating,
damage to carburettor may occur.
2. Turn Idle adjust screw (D) anticlockwise until
idle adjust screw tip just touches throttle plate.
Then turn it clockwise 1 3/8 turns.
NOTE : The initial carburettor settings for idle
adjust screw, L and H mixture needles are
intended to start and run the engine before making
final carburettor adjustments to meet Emission
Directive. Actual turns required for engine
operation may vary.
CS-550