Two metal engine pistons with piston rings and wrist pins laid out on a white background, showing a piston kit assembly.

M-8 CP Forged Pistons

$650.00

Built for serious performance, CP’s Harley-Davidson M-8 pistons are precision-machined from premium 2618 forged aluminum alloy, the industry standard for high-performance and racing applications. This heat-treated alloy delivers exceptional strength, durability, and reliability under extreme cylinder pressures and high load conditions.

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Description

Each piston is designed with a 12.0:1 compression ratio when used with a Gen 1 M-8 cylinder head featuring an 88.6cc combustion chamber, providing an ideal foundation for naturally aspirated and performance engine builds.

Every piston kit includes:

  • Forged pistons
  • Wrist pins
  • Pin locks
  • Piston rings

Important: Included piston rings are not compatible with Nikasil plated cylinders.

Proudly Made in the USA.

Features

  • Precision forged from premium 2618 aluminum alloy
  • Heat treated for maximum strength and durability
  • 12.0:1 compression ratio (88.6cc Gen 1 chamber)
  • Designed for high performance and racing applications
  • Complete kit includes pistons, pins, locks, and rings
  • Made in the USA

Specifications

Engine Size Bore Compression Height Dome/Dish CC CR Weight (g)
124CI 4.25" 1.143" 5.48 12.0:1 469
128CI 4.25" 1.080" 2.75 12.0:1 444
131CI 4.31" 1.080" .39 12.0:1 474
139CI 4.50" 1.143" -4.79 12.0:1 532
143CI 4.50" 1.080" -7.6 12.0:1 502

Additional information

Shipping Weight 2 lbs
Shipping Dimensions 10 × 7 × 6 in
Engine Size

124ci, 128ci, 131ci, 139ci, 143ci

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