Wiseco SK1366 Top End Kit Yamaha Snowmobile 12.5:1 Compression Forged Piston

The Wiseco SK1366 is a high-performance top end kit engineered for Yamaha snowmobiles (2005–2012) running a 12.5:1 compression ratio. Designed specifically for the demands of snocross and cross-country racing, this kit delivers the strength, precision, and durability that competitive snowmobile applications require.

USA-Forged for Maximum Performance:

• Forged in-house in the USA — Wiseco manufactures all pistons and forge tooling domestically, ensuring complete quality control from raw bar stock to finished parts
• Superior strength-to-weight ratio — Forged construction produces condensed, aligned grain structure for higher mechanical properties and resistance to impact and fatigue
• Skirt coating included — Factory-applied skirt coating reduces friction and improves break-in performance
• 12.5:1 compression ratio — Optimized for high-output Yamaha two-stroke snowmobile engines (2005–2012)
• Dyno-tested design — Developed through in-house dynamometer testing and rigorous R&D, incorporating advanced shapes and coatings
• Catastrophic failure resistant — Unlike brittle cast pistons, Wiseco forgings flex under stress rather than cracking, providing a critical safety margin in racing conditions

Wiseco forged pistons outperform cast alternatives by offering a denser grain structure aligned to the geometry of the part, resulting in significantly better fatigue resistance and impact toughness. This makes the SK1366 the ideal choice for riders pushing their Yamaha sleds to the limit on the race course or the trail.