131" | 124" | 117" Monster Big Bore Kits / Twin Cam

Revolution Performance Monster big bore cylinder kits in 117", 124", and 131" for '99-'17 Twin Cam motors.

When bolt-on displacement is not enough, the Monster kits go bigger. Revolution Performance builds these NSC plated aluminum cylinders for '99-'17 Twin Cams in three big inch configurations, each running a specific bore and stroke matched to your head chamber volume. No sleeving means the larger bores are possible, and the NSC plating keeps friction and temperatures down. Offered in black with highlighted fins or granite. All Monster kits require case boring.

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

• 131": 4-1/4" bore, 4-5/8" stroke with 7.669 rods, 11.2:1 (86cc heads) or 10.6:1 (95cc heads)
• 124": 4-1/4" bore, 4-3/8" stroke, 11.2:1 (86cc heads) or 10.4:1 (95cc heads)
• 117": 4-1/8" bore, 4-3/8" stroke, 10.5:1 (86cc heads) or 9.8:1 dished (95cc heads)
• All kits require case boring

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.