Wiseco 4552M08100 Forged Piston Kit Yamaha Overbore - FJ1100/FJ1200 81mm 4mm 10.25 1

The Wiseco 4552M08100 is a forged high-performance piston kit engineered for the Yamaha FJ1100 and FJ1200 inline-four engines. This kit provides a 4.00mm oversize bore of 81.00mm (up from the stock 77.00mm) with a compression ratio of 10.25:1, making it ideal for engine rebuilds requiring a performance upgrade or cylinder re-sleeving.

Key Features:

• Forged high-silicon aluminum alloy construction for superior strength, durability, and heat resistance
• 81.00mm bore diameter — 4.00mm over stock (standard bore: 77.00mm)
• 10.25:1 compression ratio for improved power output
• 63.75mm stroke for 1,314cc total displacement
• Innovative forging design and piston skirt profile optimized for maximum horsepower and torque
• Engineered, forged, and machined in the USA in Mentor, OH
• Dedicated forgings deliver an optimized strength-to-weight ratio

Kit Contents:

• 3189XG — 81.00mm ring set
• CW18 — Round wire pin locks, 18mm (pair)
• S278 — Piston pin, 18mm x 2.472 in.

Important Notes:

• Cylinder sleeving is required for installation of this oversize piston
• Crankcase cleanup is required
• Kit number: K1314

Wiseco piston kits are built to the tightest tolerances for a reliable, high-performance engine rebuild. This kit is the complete solution — piston, rings, pin, and circlips included — so you have everything needed for a successful top-end build.