Wiseco 4817M09200 Forged Piston Kit Bore CR Triumph Bonneville - 92mm 10.5 1

The Wiseco 4817M09200 is a 4-stroke forged piston kit designed for the Triumph Bonneville, America, and Speedmaster. Featuring a 92.00mm bore and 10.5:1 compression ratio, this kit is purpose-built to deliver a significant displacement upgrade from the stock 790cc engine to a 904cc configuration — a proven big bore build for Triumph parallel-twin riders seeking more power and torque.

Key Features:

• Engineered, forged, and machined in the USA — manufactured at Wiseco's facility in Mentor, OH
• High-silicon forged aluminum alloy construction for maximum strength and reduced weight
• Dedicated forgings designed specifically for the Triumph 790cc engine architecture, optimizing strength-to-weight ratio
• Improved tensile strength over cast pistons extends service life under high-performance conditions
• Precision skirt design promotes maximum ring seal and supports horsepower and torque output
• 92.00mm bore — 6.00mm oversize from stock 86.00mm bore
• 10.5:1 compression ratio with -3.5cc dish for compatibility with stock cylinder heads
• Kit includes: forged piston(s), rings (ring set 3622XR), wrist pin(s), and circlips

Important Notes:

• This is an oversize piston — cylinder boring or sleeving is required for installation
• Sold as individual piston kit; a complete big bore build typically requires two units
• OEM cross-reference: Wiseco CK149 big bore kit (complete kit with sleeves and gaskets sold separately)

Wiseco has been a trusted name in forged piston technology for powersports applications for decades. The 4817M09200 is the go-to piston for Triumph Bonneville owners looking to maximize displacement, compression, and overall engine performance.