70SZ-H Cylinder Sleeve Service Part OS27003100 for Nitro Engines O.S. Engine  [OS27003100]

Durable replacement sleeve for 70SZ-H nitro units

This replacement cylinder liner fits O.S. Engine 70SZ-H series nitro motors and acts as the internal sleeve the piston runs against. It is intended for restoration work when the original bore shows wear or scoring.

As a like-for-like replacement, the liner returns the bore to the correct running clearance without changing piston or crankcase geometry. Fitment requires removing the head and piston, extracting the old sleeve with care, checking seating surfaces and seals, then installing the new liner squarely to keep the bore concentric. Refit components to the engine maker's torque and sealing specifications.

In maintenance cycles the liner is a common service item: replacing a worn sleeve will often recover compression and smooth combustion, extending engine life and delaying major repairs. Verify piston clearance and complete a methodical break-in to ensure longevity and proper sealing.

This single-purpose sleeve is aimed at hobbyists and tuners performing routine engine rebuilds on 70SZ-H nitro engines, providing a straightforward path to recover bore condition.