You don’t have to spring for a new bike to keep up with 103s, 110s and M8s, just breathe some new life into your TC88! Our Muscle 98 top-end packages for 88″ engines will reliably flat-out smoke a bigger factory engine – mile after mile, year after year.

Smooth, linear power is extracted from the TC88 with the installation of Zipper’s Muscle 98 engine kit. This complete performance package includes precision cylinder boring, forged big bore pistons, Zipper’s CNC ported heads with oversize valves, Red Shift cams, adjustable pushrods, and all gaskets. Kits for 2001-up Delphi EFI-equipped bikes include a pre-mapped replacement ThunderMax® ECM with AutoTune and MaxFlow air cleaner assembly. 1999-2001 Touring models originally equipped with Magnetti-Marelli EFI also include conversion parts required for the installation of an included single-throat throttle body, manifold, air filter assembly and ThunderMax with AutoTune, which replaces the Marelli components entirely.

All kits are available with gear drive cams if desired; a hydraulic cam chain conversion is also available. This Muscle 98 kit includes a new ThunderMax® ECM loaded with a dedicated base map developed by Zipper’s specifically for this kit and the chosen exhaust system. What you feel is super smooth power and drivability at any RPM due to the extra-wide torque curve and our high-resolution base map. Twist the grip on your Twin Cam® and unleash the power – It’s a blast to ride!

All kits can be purchased whole or in any combination of desired components, please contact our sales department at 410-579-2828 for more details and pricing.

This kit uses your factory head and cylinder cores sent in for modification, expect 1-2 weeks completion time. We keep exchange heads and cylinders in stock already modified for quicker turn-around; parts must be in nearly perfect cosmetic condition, expect the same from us. You can also purchase heads and cylinders outright (without supplying a core set). We will supply clean, reconditioned factory castings for your application – add part # 517-010 (cylinders) and 517-015 (heads) to your order.


Not legal for sale or use in California on any pollution controlled motor vehicle.

Not legal for sale or use on any EPA pollution controlled motor vehicle.

*To ensure you enjoy a premium experience, Please fill out a Build Sheet/Job Order Sheet prior to completing an order on the website.
Click here for Zipper’s Build Sheet/Job Order Sheet

Weight 1 lbs
Emissions Compliant

Country of Origin

Engine Type


Fuel / Air


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