Piston Kit for 4-Stroke

Bring your 4-stroke engine back to strong, dependable performance with the PROX 4-Stroke Piston Kit. This kit is built for riders who want a precise, service-ready solution for a top-end refresh—helping restore compression, reduce blow-by and keep power delivery consistent. With modern CNC machining and a carefully chosen low-expansion alloy, you get a piston that’s made to fit correctly and run smoothly under demanding riding conditions.

Whether you’re rebuilding after hours of racing or doing preventative maintenance, this kit simplifies the job by including the essential components you need in one package.

Key features:

• ✅ Complete kit – includes piston, rings, wrist pin and circlips
• ✅ Precision CNC-machined – produced on state-of-the-art CNC equipment for accuracy
• ✅ Low expansion / low friction alloy – supports stable clearances and smooth operation

Benefits of use:

• 🔹 Restores top-end performance by renewing critical wear components
• 🔹 Saves time during rebuilds with all key parts included in one kit
• 🔹 Built for reliability with materials and machining aimed at consistent fit and durability

Technical specifications:

• 📌 Engine type: 4-Stroke
• 📌 Displacement: 250 cc
• 📌 Bore size: 77.00 mm
• 📌 Piston size: 76.97 mm
• 📌 Compression ratio: 13.5:1
• 📌 Material: Aluminum alloy
• 📌 Skirt coating: Non-coated
• 📌 Size/type: Standard (Standard Size B)
• 📌 Brand / Part No.: PROX 01.4337.B

Why choose this product?

• ⭐ A proven, rebuild-ready piston kit from PROX
• ⭐ Accurate machining and rider-focused materials for dependable results
• ⭐ Ideal for planned maintenance intervals and performance restoration