O.S. Engine OS22512000 Precision Crankshaft for 25AX Engine Rebuild  [OS22512000]

25AX Crankshaft Replacement Overview

This unit is the O.S. Engine crankshaft referenced by model number OS22512000 and serves as a direct replacement for 25AX-series O.S. engines. The paragraphs below address fit checks, installation guidance, and the crankshaft's part in routine maintenance or tuning preparations for small nitro RC engines.

Fit and compatibility: check the engine's stamped model code or the service manual to confirm 25AX compatibility before fitting. The crankshaft is supplied as a single rotating assembly intended to replace a worn or damaged unit during an overhaul. Inspect the crankcase seating faces and mating surfaces for wear and correct alignment prior to assembly.

Installation notes: when fitting the replacement crankshaft, examine crankpin bearings, crankcase seals, and clean oil passages of any debris. Set correct endplay and bearing preload per the engine service instructions. After initial assembly, rotate the crankshaft by hand to ensure smooth, unrestricted movement before the first run.

Tuning and maintenance role: fitted correctly, the crankshaft restores stable rotation and timing, improving the baseline for carburetion and ignition adjustments. Replace the crankshaft as part of a full rebuild when internal wear begins to affect performance or reliability.

Use this part for restoring O.S. 25AX engines and follow standard rebuild checks to ensure correct fit and reliable operation.