VHM High-Compression Cylinder Head Insert for Yamaha YZ125 & Fantic XX125 – 11.00cc

The VHM AE32100-C 11.00cc cylinder head insert is an optional higher-compression combustion chamber developed for Yamaha YZ125 and Fantic XX125 2-stroke motorcycles equipped with the VHM AA33077 cylinder head.

Compared with the standard VHM AE32100-E 11.20cc insert, the smaller 11.00cc 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 strong bottom-end response is essential for maintaining momentum. The trade-off is reduced top-speed and over-rev potential compared with a larger-volume, lower-compression insert.

The AE32100-C features a 0.00 mm piston height, 0.90 mm squish, a 12° 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 the engine setup to different track conditions or performance requirements.

The insert is precision-designed for the VHM AA33077 cylinder head and features an engraved part-number reference for easy identification during servicing and engine tuning.

This insert is not compatible with the OEM cylinder head and must be used with the VHM AA33077 head.

Key Features

• 11.00cc high-compression combustion chamber increases low- and mid-range torque
• Improves acceleration and provides stronger engine response when exiting corners
• Ideal for deep sand tracks and conditions requiring increased bottom-end power
• Quick-change VHM insert design allows easy adjustment of engine characteristics
• Precision engineered exclusively for use with the VHM AA33077 cylinder head

Technical Specifications