Shindaiwa 357 Service Manual download pdf (Page 26)

Q Shindaiwa Inc. 1995

26

300 and 300S–

Adjusting the

WYM

Section 3 Carburetors

Idle Speed Adjustment (Figure 3.6)

STEP 1. Start the saw and warm the engine to

operating temperature.

WARNING!

The saw chain can rotate whenever the

saw is started!

STEP 2. Use a screwdriver to turn the idle

speed adjustment screw in or out for an

engine idle speed of 3000 rpm ±100 rpm.

Idle Mixture Adjustments (Fig. 3.7)

The WYM carburetor used on model 300 and

300S saws uses a single nozzle for both high

and low speed operation.

■ Idle mixture for these saws is adjusted by

raising and lowering a threaded low idle

needle located in the center of the

carburetor’s barrel valve.

■ High-speed mixture is determined by the

size of the replaceable main jet orifice in

the carburetor body, and is not otherwise

adjustable.

Adjust idle mixture as follows:

STEP 1. Start the saw and warm the engine to

operating temperature.

STEP 2. Idle mixture adjustment is made in

1/8-turn increments, and is determined by

rotating the low idle needle in and then out to

locate a midway position between “lean idle”

and “rich idle” operation.

CRB-73

Figure 3.6 300/300S Idle Speed Adjustment

CRB-72

Figure 3.7 300/300S Idle Mixture Adjustment

Idle Speed

Screw

Air Cleaner

Cover

Choke

Dust Cap

Throttle

Body

Outright failure of any carburetor is unusual,

as most carburetor problems can be traced to

debris or other fuel-related problems.

■ Carburetor teardown should be performed

in a clean and well-lighted area, with all

parts contained in a small tray.

■ Carburetor components can be easily

misplaced or damaged through careless

handling or storage. Be aware that varia-

tions can exist even within a single carbure-

tor model, so be sure to refer to the appro-

priate Illustrated Parts List (IPL) during both

assembly and disassembly.

■ During disassembly, closely examine

internal nozzles and passageways for signs

of accumulated dirt or debris. Inspect

diaphragms and other non-metallic compo-

nents for possible damage from exposure

to stale fuel/fuels with an unusually high

alcohol content.

General Service

Notes

(all models)

CARBURETORS

Low Idle

Needle

1 2 ... 21 22 23 24 25 26 27 28 29 30 31 ... 137 138

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