5 x 11 x 4 mm Performance Ball Bearings Hirobo HI2500087 — 2 pcs  [HI2500087]

Small bearings that sharpen control and smoothness

The Hirobo HI2500087 is a 5 x 11 x 4 mm ball bearing supplied as a pair, intended for use in small helicopter rotating parts and compact model drivetrains. Installing fresh bearings can reduce friction and make control inputs feel crisper.

Apply these 5 x 11 x 4 mm bearings in rotor heads, tail assemblies, mini gearboxes, or other rotating linkages where compact sealed bearings are required. The two-piece pack supports swapping both sides at once or keeping a spare for quick tuning sessions.

Tuning tips: after fitting, check for free spin and minimal lateral play, and run a trial to confirm any vibration reduction. Avoid pressing the bearing in off-axis; ensure correct shaft and housing fits and use light lubrication only if the setup calls for it. Proper bearing choice can noticeably affect flight stability and responsiveness.