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Top End Components

Unlock the hidden potential of your engine with powerful Top End upgrades from Zipper’s Performance Products. Zipper’s Performance keeps specially CNC-machined heads in stock for super-quick turnaround (on an exchange basis) for Twin Cam® and Sportster® engines. Twin Cam® big bore cylinder conversions for 88 to 95” and 98" plus 96 to 103” and 107" fitted with forged pistons in many different compression ratios for fast turnaround or exchange. Zipper’s Performance also stocks pistons, valves, guides, valve spring kits, and other critical top end parts from the industry’s most renowned manufacturers.
  1. Be the first to review this product

    As low as: $23.95

    Zipper’s has developed 3-13/16” bore aluminum alloy cylinders for 883 and 1200 engines to increase the engine size to 88” with the stock stroke crankshaft. In compliance with ARB emissions laws, this product is not sold or shipped to California.
  2. Be the first to review this product

    Replace your factory powdered-metal retainers and stamped keys with these highly durable, high quality chrome moly forged spring retainers and steel keys. Don’t risk a catastrophic failure with substandard stock parts in your performance application!
  3. Be the first to review this product

    From: $65.90

    To: $345.34

    These superb valves are one-piece forged from a racing grade stainless steel alloy with a hard black finish and a bearing quality hardened tip at the end of the stem to prevent premature wear with high-lift applications.
  4. Be the first to review this product

    From: $83.90

    To: $1,170.90

    When it comes to high performance valves, Pro-Street out shines the competition. One-piece stainless impregnated by a special German process (.002 deep and .0002 surface build-up) to improve wear performance in cast iron or nickel-bronze guides.