Hatroi HA237 Copper Gasket for #643 #644 YS4C-63~70 OS4C-70~81 Replacement  [HA237]

Dedicated copper gasket for glow engine sealing

This HA237 copper gasket from Hatroi is supplied as a replacement sealing washer suitable for the engine codes listed in the product title. It is intended to re-establish a sealing surface between the cylinder head and block during maintenance or rebuild procedures.

The gasket fills microscopic irregularities at the joint to help maintain compression and to reduce external leakage that can develop after disassembly or extended running. Confirm the engine model codes in the name to ensure fit before purchasing.

Simple fitment notes: remove old gasket residue, clean both faces thoroughly, locate the copper washer flat and central to the bolt pattern, and assemble following the engine maker's torque sequence. Do not over-tension bolts; perform a conservative run-in and then verify torque after the engine reaches operating temperature.

As part of tuning or diagnostic work for low compression, swapping in a new HA237 copper gasket is a standard step to check whether sealing failure is responsible rather than internal wear or damage.