Performance Cylinder Liner for 70SZ-H - OS27003100 O.S. Engine  [OS27003100]

Performance-oriented liner for 70SZ-H rebuilds

This cylinder liner is a replacement sleeve designed for O.S. Engine 70SZ-H series nitro engines, providing the running surface for the piston. It is intended for rebuilds where bore condition needs restoring to recover performance.

As a direct-fit replacement, the liner brings the bore back to correct clearances while preserving piston and crankcase geometry. To fit, remove the cylinder head and piston, extract the old liner per your service routine, inspect sealing surfaces, and press the new liner straight and square to maintain concentricity. Reassemble following the manufacturer's torque and sealing guidelines.

From a tuning perspective, installing a fresh liner can restore compression and tighten throttle response, helping you reach expected engine behavior again. After installation, measure piston-to-wall clearance and carry out a staged break-in to confirm fit and tune adjustments.

Intended for enthusiasts and tuners, this liner is a practical service part for restoring bore integrity and returning performance to 70SZ-H nitro engines.