Hatroi HA602 Nut for #643 #644 and YS4C-63 OS4C-70 RC fittings  [HA602]

Replacement nut for RC fittings

This Hatroi HA602 nut is an RC-scale replacement part intended for use with the matching assemblies listed in the product name such as #643, #644, YS4C-63 and OS4C-70. It serves as a direct fastening component for model engine and related fittings where the original nut is lost, worn, or being swapped during routine maintenance.

Compatibility is limited to the codes shown, so confirm the part number on your model before ordering. The nut's role is mechanical: it secures mating studs and fittings, preserves alignment, and helps control vibration transfer that can affect idle stability and tuning consistency on RC power units.

Installation is straightforward for hobby workshop tasks. Clean mating threads, engage the nut by hand to confirm correct fit, then bring it to a snug fit without over-torquing to avoid thread damage. After initial installation check for proper seating and retighten after a short test run as part of regular maintenance checks.

For tuning and setup, treating this nut as a basic service spare is advised: replacing worn fasteners can prevent misalignment and erratic behavior, and keeping matching hardware on hand speeds swap-outs at the track or field.