RC Fitting Nut HA602 - Hatroi Compatible with #643 #644 YS4C-63 OS4C-70  [HA602]

Service nut for model fittings

The Hatroi HA602 nut is an aftermarket replacement intended for the part numbers listed in the product title: #643, #644, YS4C-63 and OS4C-70. It provides a straightforward fastening solution where the original nut is unavailable or worn.

Fitment is limited to the specified codes, so confirm compatibility on your model before purchase. The nut's mechanical job is to secure mating studs and components, preserve correct alignment, and limit vibration transfer that can influence tuning consistency on small RC engines.

Installation is simple for common hobby tasks. Ensure threads are clean, hand-thread the nut to verify correct engagement, then tighten to a sensible snugness without over-torquing. Check seating after a short test run and retorque if needed.

Keep this nut as part of your maintenance kit: replacing compromised fasteners helps prevent misalignment and erratic behaviour, and having spares on hand speeds repairs during track or field use.