Find A Local Dealer




S&S Cycle logo
0 Items

4 1/8" Bore Special Application Crankcases

Dealer Only Item

Facebook Twitter

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.

There are no customer reviews for this product. However, you can be the first person to add a review for this product.

Add Review
Add Review

(Your browser will be redirected back to this page)