Wiseco SK1321 Pro-Lite Forged Piston Kit for Polaris - 77.25mm 2-Stroke 600

The Wiseco SK1321 is a Pro-Lite forged 2-stroke piston kit designed for Polaris 600 snowmobile engines with a 77.25mm standard bore (piston part number 2437M). Built in the USA using Wiseco's fully in-house forging process, this kit delivers the strength, durability, and precision demanded by snocross competitors and high-performance recreational riders alike.

Wiseco's Pro-Lite piston design features a unique piston shape engineered for stability with minimal friction drag, and an ultra-lightweight forging profile that translates directly to sharper throttle response and increased torque output. Each piston is CNC-machined for optimal cam shape and profile, maximizing horsepower while extending service life.

Why Forged vs. Cast?

Wiseco starts with aerospace-grade, high-silicon low-expansion aluminum. The forging process compresses and aligns the material's grain structure to the geometry of the part, producing superior mechanical properties including resistance to impact, fatigue, and thermal stress. Cast pistons, by comparison, have no aligned grain structure and are prone to catastrophic failure when material yield strength is exceeded. Wiseco's forgings are engineered to survive the abuse of extreme motorsport conditions where cast alternatives simply cannot.

Key Features:

• 77.25mm standard bore — piston number 2437M, ring set 3040KD
• Pro-Lite forged construction — CNC machined for optimal cam shape and profile
• Aerospace-grade aluminum alloy — high silicon, low expansion for superior strength and heat transfer
• Horizontal slot-pin oiling — reduces friction and provides scuff resistance
• Pressure seal groove — maximizes ring seal for improved compression
• Diamond-turned finish — CNC precision ensures zero size variation
• 100% USA forged and manufactured — Wiseco controls the entire process from raw bar to finished part
• In-house dyno tested — validated through Wiseco's own R&D facility

Kit Includes:

• Forged piston(s)
• Piston rings
• Taper-wall wrist pin(s)
• Circlips
• Top-end gasket kit

Note: Wiseco rings are piston-specific and are not interchangeable with other ring types. Always use Wiseco rings with Wiseco pistons.