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Harley-Davidson Twin Cam 103 Wiseco Piston Kit – 3.875 in. Bore

Your Price: $468.27

SKU: K2790

Estimated Shipped Date 3-4 Weeks

Wiseco 4 Stroke Forged Series Piston Kit, 3.875 in. Bore, 9.6:1 CR

V-Twin performance has been around since some of the earliest days of motorcycle racing and engine modification, and Wiseco has been there since the beginning. Applying over 80 years of experience, Wiseco has fine-tuned its V-Twin pistons for each specific engine platform to optimize performance and durability. From reliable rebuilds to all-out race, Wiseco has the pistons for your V-Twin build.

  • Engineered, forged, and machined in the USA in Mentor, OH
  • Improved tensile strength of forged material optimizes strength and service life
  • Designed and built specifically for each V-Twin engine platform
  • Optimized compression ratio to fit your build and performance goals
  • Wrist pin, rings and circlips included

GTIN: 00193564150332

Product Series

4 Stroke Forged Series

Included Components

Piston #40184PS, Ring Set #3875VMF, Wrist Pin #927-2250-17-52C, CirClip #W5752

Bore Diameter

3.875 IN

Piston Diameter

3.872 IN

Compression Ratio Actual


Piston Material


Skirt Coating


Piston Oversize

0.125 IN

Instructions: Enter a value in the un-shaded boxes below as they pertain to your engine.
Note: For pistons BELOW the block @ TDC – value in box must be a POSITIVE number (.000)
Note: For pistons ABOVE the block @ TDC – value in box must be a NEGATIVE number (-.000)
Note: For a DISH piston – value in box must be a POSITIVE number (0.0)
Note: For a DOME piston – value in box must be a NEGATIVE number (-0.0)
Note: Manipulate the DOME/DISH & PISTON to DECK volumes to get the ratio you want.
Enter the number of cylinders of your engine
Finished bore of your engine
Stroke of your engines crankshaft
Rod Length
Ctr. to Ctr. length of your connecting rods
Gasket Bore
Head Gasket bore diameter
Comp. Gasket
Compressed Head Gasket thickness
Block Deck Height
Center of main bearing bore to top of block
Top Ring Down
Top of 1st ring to top of pistons(FLAT)
Chamber Volume
Cylinder Head chamber volume in CC’s
Dome/Dish Volume
DOME (-) or DISH (+) vol. (theoretical) in CC’s
Piston to Deck
Top of BLOCK to top of piston (FLAT) @ TDC
Click “Calculate” for dimension results.
Total Volume
Cylinder Volume
Total cylinder volume in CC’s =
Clearance Volume
All effective vol. above block deck @ TDC in CC’s =
Gasket Volume
Volume of your head gasket in CC’s =
Top Ring Volume
Total volume above the top ring @ TDC in CC’s =
Deck Volume
Volume of area above the pistons @ TDC in CC’s =
Piston Top Land
Piston top land diameter for volume calculations =
1/2 Stroke
1/2 stroke of your engine’s crankshaft in inches =
Compression Ht.
Ctr. of piston pin to top of piston (FLAT) in inches =
Cubic Inches
Cubic inch displacement of your engine =
For the given dimensions, your compression ratio