61ST-H Engine O-ring Service Pack YSS7146 for YS Engine  [YSS7146]

O-ring service pack for 61ST-H tuning

The O-ring pack from YS Engine carries model YSS7146 and is matched to the 61ST-H reference. It provides replacement sealing rings for compatible 61ST-H engine assemblies in radio-controlled models, useful when preparing the engine for extended tuning sessions.

Install this kit during regular servicing or when removing aged seals prior to setting needle and idle settings. Fresh O-rings help stabilise fuel delivery and crankcase pressure, which supports repeatable tuning and consistent run behaviour. Confirm the 61ST-H identifier on your engine to ensure correct fit.

Installation follows standard RC engine procedures: clean seal grooves, apply minimal lubricant to new rings to prevent pinching, and reassemble carefully while checking clearances. The set is a maintenance item that aids reliable tuning rather than a direct performance upgrade on its own.