ProX 4-Stroke Piston Kit (76.97mm / Size B) 01.4337.B - Kawasaki KX250F 2006-2009

Product Description

The ProX 01.4337.B 4-Stroke Piston Kit provides a precision-engineered top-end component package designed specifically for the Kawasaki KX250F. Engineered for riders servicing their 250cc power plant, this standard Size B assembly delivers an exact 76.97mm outer diameter dimension to match cylinders requiring a 77.00mm standard bore tolerance. Each package arrives as a complete assembly including the piston, matched piston rings, wrist pin, and circlips for a comprehensive top-end overhaul.

Manufactured utilizing a dedicated low-expansion, low-friction aluminum alloy, this piston is precision machined on modern CNC equipment to maintain dimensional stability under intense thermal loads. The non-coated skirt design and 13.5:1 compression ratio mirror the mechanical requirements of the four-stroke engine platform, ensuring proper combustion chamber sealing, minimal skirt friction, and consistent output throughout the RPM range.

Top Features: ProX Piston Kit

• Manufactured from low-expansion, low-friction aluminum alloy to withstand high thermal cycling without distorting.
• Machined on computer numerical control (CNC) equipment to maintain exact tolerances for a 77.00 mm standard bore.
• Engineered to deliver a 13.5:1 compression ratio tailored for the four-stroke 250cc combustion chamber profile.
• Complete rebuild kit configuration includes the aluminum alloy piston, matched rings, wrist pin, and retaining circlips.

Please review the detailed compatibility data below to ensure an exact fitment match for your motorcycle before finalizing your purchase.

Fitment List

Frequently Asked Questions

Q: What components are included in the ProX 01.4337.B piston kit?
A: The kit contains one 76.97mm Size B aluminum alloy piston, a set of piston rings, a wrist pin, and two circlips.

Q: What cylinder bore diameter and compression ratio are designed for this piston?
A: This piston is designed for a standard 77.00mm cylinder bore and produces a 13.5:1 compression ratio.

Expert Pro-Tip: Always measure the cylinder bore with a bore gauge at three heights (top, middle, bottom) and in two directions to verify the cylinder is within service limits and round before selecting your B-sized piston. When installing the piston rings, verify the end gap in the cylinder with a feeler gauge, stagger the ring end gaps according to the factory manual, and ensure the circlip end gaps point vertically at 6 o'clock or 12 o'clock.

Recommended Pairings:

• Kawasaki KX250F Performance Parts & Upgrades
• Kawasaki 4-Stroke Performance Parts
• Motorcycle Tools & Accessories

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