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Section 3 MAINTENANCE   (con't)

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Remove cover. Clean points with a carborundum contact point stone. Then insert a hard finished card or pied, of paper and close and open points. The paper will absorb any dirt or filings on the points. Adjust breaker points as follows:

a. Rotate crankshaft until points open to widest gap. 
b.. Loosen lock nit illustrated below until it is just snug.
c. Rotate breaker point screw to obtain .020" gap. 
d. When gap is .020" tighten locknut.
e. Replace breaker box cover.

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7.  CLEAN SPARK PLUG - Clean and reset gap at .030" every 100 hours of operation.
CAUTION: Blast cleaning of spark plugs in machines that rise abrasive grit is not recommended. Spark plugs should he cleaned by scraping or wire brushing and washing with a commercial solvent or gasoline.

Loosen thumb screw below filter bowl. Remove and clean filter bowl and screen. Open shut-off valve to see if fuel flows freely from the tank. IMPORTANT: If you find a gummy, varnish-like substance use alcohol or acetone to dissolve it

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Minor carburetor adjustment may be required to compensate for differences in fuel, temperature, altitude and load.

Initial Adjustment

Turn needle valve clockwise until it just closes. 
CAUTION: Valve may be damaged by turning it in too far.
Now open needle valve 1-1/2 turns counterclockwise. Close idle valve in same manner and open it 1/2 to 1/4 turns. This initial adjustment will permit the engine to be started and warmed up prior to final adjustment.

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Final Adjustment.  Turn needle valve in until engine misses (lean mixture), then turn it out past smooth operating point until engine runs unevenly (rich mixture). Now turn needle valve to the mid-point between rich and lean so the engine runs smoothly. Hold throttle at idle position, set idle speed adjusting screw until fast idle is obtained (1200 RPM). Hold throttle in idle position and turn idle valve in (lean) and out (rich) until engine idles smoothly. Then reset idle speed so that engine idles at 1200 RPM. Release throttle - engine should accelerate without hesitation or sputtering. If engine does not accelerate properly, re-adjust needle valve to a slightly richer mixture.


[Source:  Briggs & Stratton Operating and Maintenance Instructions, Models 243431 to 243434, Form No. 27030 - 74.]



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