Namura Standard Bore Size A Top End Kit for KTM 250 SX, EXC, XC, XC-W 66.4mm

Standard Bore Size A Top End Kit for KTM

This top end kit delivers a direct-replacement cylinder, piston, and rings for KTM 250 SX, EXC, XC, and XC-W models, featuring a 66.4mm standard bore size A for restoring factory compression and power.

Overview

This top end kit is a complete piston-and-cylinder assembly designed for KTM 250 two-stroke off-road and motocross bikes. It restores original performance by replacing worn top-end components with a 66.4mm bore and matched parts. Ideal for riders rebuilding their KTM 250 engine after hours of hard riding.

Built For Performance

• Precision-machined cylinder with a 66.4mm bore for exact OEM fitment
• Includes piston, rings, wrist pin, and circlips for a complete top-end overhaul
• Cast piston with low-friction ring pack ensures reliable break-in and longevity
• Designed for standard bore size A to match factory specifications
• Manufactured to strict tolerances for consistent compression and power delivery

Fits These Machines

• for KTM 250 SX
• for KTM 250 EXC
• for KTM 250 XC
• for KTM 250 XC-W

On-The-Job Use

• Motocross racing on tracks with high-rev demands
• Enduro and cross-country trail riding requiring reliability
• Hard off-road use where top-end durability is critical
• Rebuilding a high-hour engine to restore performance

Specs At A Glance

Good To Know

Q: Does this top end kit include a gasket set? A: This kit includes the piston, rings, wrist pin, and circlips but does not include a separate gasket set; a top end gasket kit is sold separately.

Q: Can I install this kit without special tools? A: Installation requires basic engine assembly tools and a torque wrench; we recommend following the factory service manual for proper procedures.

Slight variation in finish or dimensions may occur between production runs, and confirm compatibility before ordering.