25AX Finned Cylinder Head - O.S. Engine OS22514000  [OS22514000]

Finned head for 25AX motors

This heatsink-style cylinder head is made as a direct replacement option for the O.S. Engine 25AX engine family. The fin array increases surface area to move heat away from the combustion zone and stabilise operating temperature.

Installation is a routine job for those familiar with glow engines: remove the factory head, clean all mating surfaces, replace or reuse the head gasket as suited to condition, and tighten the head bolts evenly. Avoid excess torque and check the head sits true before finishing.

When tuning, the improved heat transfer helps limit temperature-driven shifts in performance, making needle and jet tuning more predictable. Periodic checks of sealing faces and fasteners will maintain reliable operation.