Hirobo HI2500067 Ball Bearing Set 4 x 13 x 5 mm, 2 pcs  [HI2500067]

Precision ball bearings for small RC helicopters

This Hirobo replacement is a set of two 4 x 13 x 5 mm ball bearings sold as pcs, identified by the #624ZZ marking. They are intended as small-scale RC helicopter service parts for rotating linkages and drivetrain subassemblies where compact bearings are required.

Compatibility is general rather than model-specific, so check the shaft diameter and housing bore in your assembly before installation. The 4 x 13 x 5 mm dimension indicates inner diameter, outer diameter, and width respectively, ensure those match the part you remove.

When installing, press the bearing squarely into its bore, avoid side loads during seating, and clean the mating surfaces. If removing old bearings, use proper pullers to protect shafts and gear faces. In tuning terms, replacing worn bearings reduces play and friction, helping maintain smooth rotor and gearbox response.