S&S Cycle Billet Oil Pump for Big Twin Engines - Manual (Page 21)

21
APPENDIx: OIL LINE ROUTING
Most big twin oiling systems utilize three oil circuits: supply, return, and breather/vent. 1965-1984 models often utilize a fourth circuit for primary
chain oiling.
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Supply circuit delivers oil from tank to supply fitting of oil pump cover. See Pictures 6 & 7. In motorcycles with oil tank located above
transmission, supply fitting in oil tank is almost always located on bottom of tank at center or rear. In Harley-Davidson® Dyna
TM , Road King®
and other models with oil tank below transmission, supply line exits oil tank on bottom of primary drive side, then crosses to cam side and
connects with supply fitting on oil pump cover.
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To distinguish oil tank’s supply fitting from vent and return fittings, remove oil lines and pour small amount of oil into tank. With motorcycle
in upright position, oil will flow out supply line fitting.
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Return circuit delivers oil from return fitting in oil pump cover (See Pictures 6 & 7), through oil filter and cooler (if applicable), to return
fitting in oil tank.
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In horseshoe-type oil tanks, two fittings nearest front of oil tank are identical. Fittings may enter through upper area of tank or connect to
fittings near bottom that are attached to standpipes inside tank. These fittings are for oil return and vent lines, and in most cases may be
used interchangeably. Main exception is with oil tanks with “in tank” oil filter.
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Square oil tank used on 1965-1984 panhead and shovelhead has return line fitting in filler neck located in top center of oil tank; vent fitting
is slightly forward of return fitting. In models with oil tank located below transmission, return fitting is on top of oil tank nearest center of
motorcycle. Vent fitting is beside return fitting.
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Breather or vent circuit equalizes pressurize between oil tank and crankcase. See preceding paragraph for location of vent fitting in oil tank.
Vent line runs from vent fitting on oil tank to Hole #1 in crankcase. See Picture 33.
Picture 33
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Primary chain oiling system used on 1965-1984 big twin requires three oil lines. Chain oil supply line originates at 1⁄4” hose fitting in top of oil
pump cover (See Picture 6) and connects to 1⁄4” hose fitting near center of inner primary case. Primary housing vent line connects 3⁄8” fitting
near center of inner primary cover to tee-fitting in vent line between crankcase and oil tank. Primary scavenge line connects 3⁄8” hose fitting
at bottom, rear of inner primary cover to hole #2 (See Picture 33) in crankcase.