98" Big Bore Kits / '99-06 Twin Cam

Revolution Performance 98" big bore kit for '99-'06 Harley Twin Cam motors.

A clean displacement bump for the early Twin Cam. Revolution Performance builds this 98" kit in NSC plated aluminum with no sleeving, dropping friction and engine temperatures while adding cubic inches. It comes with domed 10.3:1 pistons for 86cc heads and a gasket set, in natural or black with highlighted fins. Requires 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

• 98": 3-15/16" bore, 4" stroke, 10.3:1, domed pistons, 86cc heads
• Fits '99-'06 Twin Cam
• Requires 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.