VHM High-Compression Cylinder Head Insert for KTM 125 SX, Husqvarna TC 125 & GASGAS MC 125 – 11.40cc

The VHM AE32257-C 11.40cc cylinder head insert is an optional high-compression combustion chamber developed for KTM 125 SX, Husqvarna TC 125, and GASGAS MC 125 2-stroke motorcycles equipped with the VHM AA33156 cylinder head.

Compared with the standard AE32257-E 11.60cc VHM insert, the smaller 11.40cc combustion chamber increases the compression ratio and shifts the engine character toward stronger low- and mid-range torque. This provides quicker acceleration, more immediate throttle response, and increased drive when exiting corners.

This torque-focused setup is particularly effective on deep sand tracks and other conditions where stronger bottom-end response helps maintain momentum. The trade-off is reduced top-speed and over-rev potential compared with the standard or larger-volume chamber configurations.

The insert features an 11.40cc combustion chamber volume, 0.00 mm piston height, 0.90 mm squish, a flat-top piston crown profile, and a Ø54 mm bore.

VHM’s interchangeable combustion chamber system allows the insert to be changed quickly without replacing the complete cylinder head, making it easier to adapt engine characteristics to different track conditions and performance requirements.

Because this insert increases compression, VHM recommends using high-quality fuel with suitable detonation resistance.

The AE32257-C is precision-designed for the VHM AA33156 cylinder head and features an engraved part-number reference for easy identification during servicing and engine setup.

This insert is not compatible with the OEM cylinder head and must be used with the VHM AA33156 head.

Key Features

• 11.40cc high-compression combustion chamber increases low- and mid-range torque
• Improves acceleration and delivers stronger engine response when exiting corners
• Ideal for deep sand tracks and traction-demanding motocross conditions
• Quick-change VHM insert design allows easy adjustment of engine characteristics
• Designed for use with high-quality fuel to help reduce the risk of detonation

Technical Specifications