Briggs & Stratton 81900 - Manual (Page 6)

SECTION fV
SECTION IV — ADJUSTMENTS (Cont'd)
InKUl Uju(tm«nt:
Dose ne«dle valvt (turn clockwite]
then open 1V& turns (turn counter­
clockwise). This initial adjustment will
permit the ermine to be started and
warmed up before makinf final ad­
justment
Final Adjustment
With engine running at normal opera­
ting speed (approximately 3000 R.P.M.
without load) close the needle valve
(turn clockwise) until engine starts to
lose speed (lean mixture). Then slowly
CARBURETOR AOJUSTMCNTS
Open needle valve (turn counter-clock­
wise), pest the point of smoothest op­
eration, until engine just begins to run
unevenly. This mixture should be rich
enough for best performance ur>der
loed.
Hold throttle in idling position. Turn
idle fpeed adjusting screw until fast
idle is obtained (1750 R.PJd.).
Test the engine under full load. If eiv
gine tends to stall or die out, it usually
if>dicates that the mixture is slightly
lean and it irtay be necessary to open
the needle valve slightly to provide a
richer mixture. This richer mixture may
cause a slight unevenness in idling-
SECTION V
PARTS AND SERVICE
eCHERAt. INFORMATION
These engines art single-cylinder, L-head, air-ceoled type.
MODEL SERIES ^
80900 to 80996
end 81900 to 81996
Bore............................................................... 2 3/8"
Stroke............................................................ 1 3/4"
Displacement............................................ 7.7 cu. in.
Horsepower......................3.0 HP mox. § 3600 RPM
The horsepower ratings listed above are established by standard I.C.E.I. procedures.
For practical operation, the horsepower loading should not exceed 85% of these
ratings. Engine power will decrease 3V^% for each i,000 ft. above saa level and 1%
for each 10 degrees above 60 degrees F.
TUNE-UP SPECIFICATIONS
Spork Plug Type AC*(»C-46;
AL>A7R; Chomp. J8.
Spork Plug Gap...............................025"
Ignition Point (àop.........................020"
Intoke Volve Cleerence . .005"-.(X)7"
Exhoust Volve Cleoronce J)09">.011"
CAUTION: Blast Cleaning of spark plugs
in machines that use abrasive grit is
not recorrunended. Spark plugs should
be cleaned by scraping
or wire brush­
ing and washirg with a commercial sol­
vent or psoline.
Major engine repairs should not be at­
tempted unless you have the proper
tools and a thorough knowledge of in­
ternal combustion angines.