GF40 Replacement Piston for O.S. Engine OS49403200  [OS49403200]

GF40 piston technical summary

The O.S. Engine OS49403200 piston for GF40 engines is supplied under the model code OS49403200 as a direct replacement for GF40 cylinder assemblies. This write-up covers basic fitment tips, the piston’s influence on compression and throttle response, and routine inspection points for hobby-level servicing.

Compatibility is indicated by the GF40 designation; the piston suits GF40-design engines and matching cylinder kits. When fitting a new piston, examine the cylinder bore and ring clearance for wear before assembly and follow the engine manufacturer's service steps to ensure correct orientation and stroke clearance. The piston is a wear item that can affect compression, so correct seating and ring condition are important for consistent engine behavior.

For maintenance, remove the cylinder head to inspect mating surfaces, confirm the piston ring(s) run freely in their groove, and verify piston-to-wall clearance. After reassembly, run a controlled break-in and monitor temperature and compression to validate the replacement. For fitment questions or additional spare parts, consult an authorized O.S. Engine dealer or the official service manual.

This piston is intended as a replacement part for GF40-series RC engines; careful inspection and correct assembly are essential for predictable tuning and performance.