128" | 124" Bolt-On Big Bore Kits / M8 Motors

Revolution Performance bolt-on big bore kits in 124" and 128" for '17-'22 Harley M8 motors.

A true bolt-on path to big M8 power. Revolution Performance builds these NSC plated aluminum cylinder kits for '17-'22 M8 motors, adding major displacement, durability, and strength without sleeving or case work. The nickel silicon carbide bore reduces friction for more horsepower, cooler running, and longer life. Choose the 128" for 114/117 motors or the 124" for the 107, in black, black granite, or black with highlighted fins.

Features

• Aerospace grade all-aluminum cylinders with a nickel silicon carbide (NSC) electroplated bore
• No sleeving, which allows for larger bore sizes
• NSC plating reduces friction for more horsepower, lower engine temperatures, and longer lifespan
• Includes a pair of NSC coated cylinders, custom forged pistons with high tension rings designed for NSC bores, and a head and base gasket set
• Replacement gasket sets available separately
• Upgraded cylinder studs and head bolts recommended
• Made in the U.S.A.

Specifications

• 128": 4-1/4" bore, 4-1/2" stroke, 11.3:1 with 88cc heads (for 17-22 M8 114/117)
• 124": 4-1/4" bore, 4-3/8" stroke, 11.2:1 with 88cc heads (for 17-22 M8 107)
• True bolt-on, no case boring required

Note: No shipping to California.

Frequently Asked Questions

Do I need to bore my cases?
Monster big bore kits require case boring. Bolt-on kits do not. Check the specific kit and ⚠️ VERIFY your case and head combination before ordering.

What head do I need?
Each displacement is matched to a specific head chamber volume. Match the kit to your heads exactly, since compression depends on it.

Are pistons included?
Yes. Each kit includes custom forged pistons with high tension rings designed for the NSC bore, plus a head and base gasket set.