Moose Offroad MSE24385B Piston Kit — 71.96 mm Cast Replica — 2018-2021 Beta 300 RR

Moose Offroad MSE24385B — High-Silicon Cast Aluminum Alloy, MOS2 Skirt Coating, and Nitride-Hardened Wrist Pin

Restore the legendary low-end torque and peak performance of your 300cc powerplant with the Moose Offroad MSE24385B Piston Kit. Specifically engineered as a high-performance OE replacement for the 2018-2021 Beta 300 RR, this 71.96 mm piston kit is the professional choice for a top-end refresh. While standard pistons can suffer from thermal expansion under heavy loads, Moose utilize a gravity-cast aluminum alloy infused with 18% silicon. This high silicone content is vital for high-displacement 2-strokes, as it significantly reduces thermal distortion and increases the piston's resistance to wear, maintaining a precise fit within the cylinder even during the most grueling enduro motos.

The MSE24385B is designed for durability from the first start. The piston skirt is treated with a high-tech Molybdenum Disulphite (MOS2) coating, which facilitates a safer break-in period by reducing friction and providing a dry lubricant barrier. To further enhance longevity, the included wrist pin is nitride-coated to create a diamond-hard bearing surface that resists galling. This comprehensive kit includes the cast replica piston, high-tensile wear-resistant rings, the hardened wrist pin, and high-tension circlips. With a stock compression ratio, this kit preserves the smooth, linear power delivery that makes the Beta 300 RR a favorite for technical off-road terrain.

• 18% Silicon Aluminum Alloy: Superior material stability reduces thermal expansion and ensures a longer piston service life.
• Molybdenum Disulphite Skirt Coating: Aids in initial lubrication and eases the break-in process to prevent premature scuffing.
• Nitride-Coated Wrist Pin: Provides an incredibly hard, wear-resistant surface for the small-end bearing interface.
• Complete Top-End Solution: Includes the cast replica piston, specialized wear-resistant rings, wrist pin, and circlips.
• Precision Fitment: Engineered for the 2018-2021 Beta 300 RR with a 71.96 mm diameter for 72.00 mm cylinders.

Moto-House MX Pro Tip:

Precision is everything when rebuilding a 300cc top end. This "B" size 71.96 mm piston is ideally suited for cylinders that have been broken in and may show a microscopic amount of wear, ensuring you maintain the ideal 0.04 mm piston-to-wall clearance. Before installation, we recommend thoroughly cleaning the cylinder ports and power valve assembly. Always install the circlips with the gap at either the 6 o'clock or 12 o'clock position to prevent centrifugal force from unseating them. For a factory-level seal, pair this kit with a fresh top-end gasket set and a new needle bearing.

Technical Specification	Details
Piston Diameter	71.96 mm (Size B)
Cylinder Diameter	72.00 mm
Material	Gravity Cast High-Silicon Alloy
Engine Type	300cc 2-Stroke

FAQ Questions

Q) Why choose a cast piston for the Beta 300 RR?
A) Cast pistons typically have higher silicone content than forged ones, which results in less thermal expansion. This allows for tighter clearances and quieter engine operation, which is ideal for the smooth power delivery Beta riders expect.

Q) Does this kit include a top-end gasket set?
A) No, this kit includes the piston, rings, pin, and clips. Gaskets and the wrist pin needle bearing are sold separately.

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