VHM Standard Cylinder Head Insert for Yamaha YZ85 – 8.40cc

The VHM AE32286-E 8.40cc cylinder head insert is the standard VHM combustion chamber configuration developed for Yamaha YZ85 motorcycles equipped with the VHM AA33176 cylinder head.

Designed for the best overall performance, the AE32286-E delivers a balanced combination of bottom-end response, mid-range torque, acceleration, and high-rpm performance. It is the all-around VHM setup for riders looking for consistent and predictable engine behavior across a wide range of motocross conditions.

The insert features an 8.40cc combustion chamber volume, +1.60 mm piston height, 1.30 mm squish, a dome piston crown profile, and a Ø47.50 mm bore.

VHM’s interchangeable combustion chamber system allows the insert to be changed quickly without replacing the complete cylinder head. This simplifies servicing and gives riders and engine tuners the flexibility to select alternative chamber volumes when different compression or power-delivery characteristics are required.

The AE32286-E is precision-engineered for the VHM AA33176 cylinder head and features an engraved part-number reference for easy identification during servicing and engine setup.

This insert does not fit the OEM cylinder head and must be used with the VHM AA33176 head.

Key Features

• 8.40cc VHM standard combustion chamber developed for balanced overall Yamaha YZ85 performance
• Delivers predictable bottom-end response, usable mid-range torque, and strong high-rpm performance
• Dome combustion chamber profile is matched to the standard Yamaha YZ85 piston configuration
• Quick-change VHM insert design allows easy servicing and combustion chamber adjustment
• Precision engineered exclusively for use with the VHM AA33176 cylinder head

Technical Specifications