Briggs & Stratton 146400 - Manual (Page 4)

Section
3
M A I N T E N A N C E (cont’d)
Dry Element Type
To clean - tap element (top or bottom) on flat surface
or wash in non-sudsing detergent and flush from inside
until water is clear. After washing, air dry thoroughly
before using. DO NOT OIL.
(?)CLEA1M CQQLUMG SYSTEM - Grass or chaff may clog
^"^cooling system after prolonged service in cutting tall
dry grasses or hay. Continued operation with a clog­
ged cooling system causes severe overheating and
possible engine damage. Remove blower housing and
clean regularly.
SPARK PLUG-Clean and reset gap at .030" every 100
hours of operation.
CAUTION: Blast cleaning of spark plugs in machines
that use abrasive grit is not recommended. Spark plugs
should be cleaned by scraping or wire brushing and
washing with a commercial solvent or gasoline.
CLEAN COMBUSTION CHAMBER every 100-300 hours of operation. The use of regular automotive fuels and con­
stant speed and toad operation, often result in a gradual build-up of tetraethyl lead deposits in the combustion
chamber. Remove cylinder head. Scrape and wire brush the lead and carbon deposits from cylinder head,* top of
piston and around valves. Use a soft brush or compressed air to remove loose deposits.
Reassemble cylinder head, gasket, cover and turn down screws finger tight Use the three longer screws around
the exhaust valve. Using a socket wrench with a 6" handle, turn all screws an additional 1/4 turn (150-175
torque). BE SURE TO TIGHTEN head mounting screws in a staggered sequence.
S e c t i o n
4
ADJUSTiVlENTS
CARBURETOR ADJUSTMENTS
Minor carburetor adjustment may be required to com­
pensate for differences in fuel, temperature, altitude
and load.
To Adjust Carburetor Turn needle valve clockwise
until it just closes. Caution: Valve may be damaged
by turning it in too far.
Now open needle valve 1-1/8 turns counterclockwise.
Close idle valve in same manner and open 1-1/8 turns.
This initial • adjustment will permit the engine to be
started and warmed up prior to final adjustment.
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 and set idle speed adjusting screw until fast Idle is
obtained (1750 RPM). Hold throttle in idle position and turn idle valve in (lean) and out (rich) until engine idles
smoothly. Then reset idle speed adjusting screw so that engine idles at 1750 RPM. Release throttle—engine
should accelerate without hesitation or sputtering. If engine does not accelerate properly, the carburetor should
be re-adjusted to a slightly richer mixture.