O.S. Engine OS49403200 GF40 Service Piston  [OS49403200]

Fit and function notes for the GF40 piston

The O.S. Engine OS49403200 is a replacement piston intended for GF40 cylinder assemblies, listed under model number OS49403200. This note highlights fitment considerations, the piston’s role in engine response, and common inspection points during a service overhaul.

Compatibility is defined by the GF40 designation; this piston is for GF40-style engines and corresponding cylinder kits. Before installation, check the cylinder bore and ring clearance for wear and follow the engine maker's service instructions to confirm correct piston orientation and stroke clearance. As a wear component, the piston affects compression and throttle characteristics, so proper seating and ring condition are critical.

During routine service, remove the cylinder head to check mating faces, ensure the piston ring(s) move freely in the groove without binding, and verify piston-to-wall clearance. After reassembly, complete a careful run-in and observe running temperature and compression to confirm suitable installation. For specific fitment guidance, contact an authorized O.S. Engine dealer or consult the service manual.

Use this piston as a standard replacement for GF40 engines, observing careful inspection and assembly for consistent engine operation.