Moose Offroad MSE24391B Piston Kit — 71.96 mm Cast Replica — 2013-2017 Beta 300 RR

Moose Offroad MSE24391B — Gravity Cast Aluminum Alloy, 18% Silicon Wear Resistance, and Molybdenum Disulphite Coated Skirts

Restore the legendary "grunt" and compression of your 2-stroke powerplant with the Moose Offroad MSE24391B Piston Kit. Engineered as a high-performance OE replacement for the 2013-2017 Beta 300 RR, this 71.96 mm piston kit is designed to return your engine to factory-spec tolerances. While many aftermarket pistons sacrifice longevity for weight, Moose utilizes a gravity-cast aluminum alloy infused with 18% silicon. This high silicon content is critical for 2-stroke applications as it significantly reduces thermal expansion and increases the piston's resistance to wear, ensuring a stable fit within the cylinder even under extreme heat.

To ensure a reliable top-end rebuild, the MSE24391B features a Molybdenum Disulphite (MOS2) coated skirt. This specialized coating acts as a dry lubricant during the critical initial break-in period, reducing friction and preventing scuffing before the oil film fully stabilizes. The included wrist pin is nitride-coated, creating a diamond-hard bearing surface that resists galling and wear. Every kit is a complete top-end solution, providing the cast replica piston, high-tensile wear-resistant rings, the nitride wrist pin, and high-tension circlips. With a stock compression ratio, this kit maintains the smooth, predictable power delivery that Beta 300 riders depend on for technical trails.

• High-Silicon Aluminum Alloy: 18% silicon content reduces thermal distortion and provides superior resistance to skirt wear.
• MOS2 Coated Skirts: Molybdenum Disulphite coating aids in lubrication and ensures a safe, scuff-free break-in process.
• Nitride-Coated Wrist Pin: Hardened bearing surface significantly increases the lifespan of the small-end bearing interface.
• Complete Rebuild Kit: Includes the cast replica piston, high-performance rings, wrist pin, and circlips.
• OE Compression Spec: Maintains the original engine characteristics and reliability of the 2013-2017 Beta 300 RR.

Moto-House MX Pro Tip:

Top-end maintenance is the lifeblood of a high-performance 300cc 2-stroke. This 71.96 mm piston is designed for a standard 72.00 mm cylinder bore. Before installation, we highly recommend measuring your cylinder with a dial bore gauge to ensure you have the proper 0.04 mm clearance. When assembling, always install the circlips with the opening facing either 12 o'clock or 6 o'clock to prevent inertia from unseating them at high RPM. Pair this kit with a fresh top-end gasket set and a new needle bearing to ensure your Beta 300 RR continues to dominate the technical terrain for seasons to come.

Technical Specification	Details
Piston Diameter	71.96 mm
Cylinder Diameter	72.00 mm
Piston Material	Gravity Cast High-Silicon Alloy
Skirt Coating	Molybdenum Disulphite (MOS2)

FAQ Questions

Q) Is this a forged or cast piston?
A) This is a Cast Replica piston. Cast pistons are preferred by many off-road riders for their higher silicon content, which allows for tighter clearances and quieter operation compared to forged alternatives.

Q) Does this kit include the top-end gaskets?
A) No, this kit includes the piston, rings, wrist pin, and circlips. Top-end gasket sets are sold separately and are required for a proper rebuild.

Moto-House MX – Choice of Champions – is located in Clermont/Montverde, FL. We are the best motocross shop in Central Florida with lightning-fast shipping.