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    Special Application Crankcases for 1992-'99 Big Twins with 4-1/8" Bore, Small Diameter Flywheels - Wrinkle Black

    Item #: 31-0037
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    Product is currently on backorder. You may still order this product. The product will ship within 7 days.


    Designed for high performance engines with cylinder bores between 4" and 4 3/8".


    • 1984–'99 big twins with 4" bore and over
    • S&S 4 3/8" bore: V126
    • S&S 4 1/8" bore: V124, V111, V117
    • S&S 4" bore: V100, V107, V113, V107T

    Features and Benfits

    • Cam chest is moved outward .250" to allow crankcases to handle large cylinder bore sizes
    • Relocated cam chest oil pick-up increases gear case scavenging and virtually eliminates oil carry-over at sustained high speeds
    • Machined to accept the stock oil filter assembly used on 1992–'99 big twins
    • A ported breather passageway and a machined breather window allows the air/oil mist to flow from the flywheel cavity to the cam chest of the engine with the least possible restriction
    • Crankcase venting can be achieved via two crankcase breathers, the cylinder heads, or both! We recommend using both crankcase breathers in engines larger than 95"
    • Clearanced for strokes as long as 5"
    • Machined for installation of a crank position sensor. This allows the cases to be used in EFI applications and also allows easy installation of S&S IST® Ignition and VFI Fuel Injection. A plug kit is included for applications that do not use a crank position sensor


    S&S® 4 1/8" BORE CRANKCASES for 1984-'99 BIG TWIN
    Crankcase Finish Deck Height Part Number
    Natural 6.000" 31-0033
    Black 31-0037
    Polished 31-0039


    Note: All S&S crankcases manufactured after June 1, 2008 do not have case interlock groove and ring and do not use case alignment studs. Case mating surface is flat, and cases are aligned with alignment dowels.

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    1992-'99 style oil pump, machined for 1984-'99 alloy primary, machined for stock or S&S EFI crank position sensor. Stock diameter only.