70SZ-H Cylinder Liner Precision Replacement - OS27003100 by O.S. Engine  [OS27003100]

Service cylinder sleeve for 70SZ-H engines

This cylinder liner is an RC-scale replacement sleeve made for O.S. Engine 70SZ-H series nitro engines. It provides the wear surface for the piston and is intended for rebuilds and routine maintenance tasks.

Manufactured as a direct replacement, the liner restores correct bore geometry and running clearances without altering crankcase or piston dimensions. For installation, remove the head and piston assembly, extract the old liner following the engine service procedure, inspect mating faces and seals, then press or seat the new liner straight to preserve bore concentricity. Reassemble using the engine maker's torque and sealing guidance.

When servicing or tuning, replacing a worn or scored liner can bring compression and combustion stability back to expected ranges, reducing the need for more invasive repairs. After fitting, measure piston-to-wall clearance and perform a careful break-in to confirm fit and sealing.

As a service-level cylinder sleeve, this liner is suited for hobbyist engine rebuilds and routine maintenance on 70SZ-H nitro RC engines, offering a straightforward way to restore bore condition during servicing.