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S&S Engines

S&S Cycle Special Application Big Bore Crankcases

Call (800-841-STAR) or E-mail for pricing

These cases are cast from aircraft grade A206 aluminum, for exceptional strength, and are precision CNC machined to maintain the highest dimensional accuracy. S&S® special application (SA) big bore crankcases for 1999–up big twins are intended for use in stock Harley-Davidson® chassis and will bolt directly to the stock Harley-Davidson® transmission in place of the stock Twin Cam 88® engine. These crankcases are recommended for any racing or high performance street application. Available in natural aluminum finish only.

Kit Contents

  • Crankcase
  • S&S crankcase breather valve
  • All required hardware for assembly

Features and Benefits

  • Can be ordered for 4.375" to 4.800" bore engines
  • Cam chest on the right side has been offset .375" — requires a special .375" longer pinion shaft
  • Deck height can be machined to the stock height of 6.000" or as high as 7.125" from the crank center line — allows for more material and greater strength between the cylinder spigot bores
  • Optional stock cam geometry — allows the engine builder to select from a wide variety of readily available cams
  • Optional special rotated S&S cam geometry—improves the pushrod angles for more direct application of force to the rocker arms, hence more accurate valve actuation. (Cases machined for this option require specially ground cams. These cams are not currently available from S&S and must be special ordered from the cam manufacturer.)

Part Numbers

4 3/8" Bore – stock geometry . . . . . . . . . . . . . . . .106-0505
Special Order* . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106-0719

Special order options:

  • 4.600" Bore – standard stock cam geometry only
  • 4.800" Bore

*Not available for Twin Cam 88B™ engines or 2006 Dyna® or any 2007 models.

S&S Cycle SA Big Bore crankcasesFlywheels for S&S SA Big Bore Crankcases

Since the cam chest is offset by .375", a special flywheel assembly with a .375" longer pinion shaft must be used. Use the special order flywheel, part #32-2141, to order flywheels for these crankcases. Specify that a S&S special application big bore crankcase will be used, so the correct .375" longer pinion shaft will be included in the assembly.

S&S Cycle SA Big Bore crankcases


Bonneville Bike

Owner - John Yeats

Driver - Eric Bennett

Engine - 133" S&S Street Pro

with S&S SA Big Bore Crankcase

S&S SA Big Bore crankcases in building stage of Bonneville bike S&S SA Big Bore crankcases in Bonneville bike
Bike in building stage
Bike on the Salt Flats
Other Customer Bikes using TCSA cases

Easy Start Cams

Harley Upgrades

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