Quick answer: The clearest way to identify a kart bearing is to record the complete marking and verify three dimensions: bore, outside diameter and width. Suffixes such as seal, shield, clearance or locking style matter, so “it is a 6203” may still be an incomplete specification.
Safety: Support the kart correctly and isolate the engine before removing wheels, axle components or bearing carriers. A rough, loose, cracked or overheating bearing should be investigated before the kart returns to service.
Read the full reference
Clean the side face gently and photograph all characters. The basic designation identifies the bearing family and size, while prefixes and suffixes can describe internal design, seals, shields, clearance and other features. Manufacturer suffixes are not always identical, so compare the full specification rather than matching only the first four digits.
Measure the bearing
- Bore: the inside diameter that fits the shaft, axle or stub axle.
- Outside diameter: the largest diameter of the outer ring.
- Width: the overall thickness across the rings.
Use a vernier caliper on clean, undamaged surfaces. If the bearing has an insert, eccentric collar, extended inner ring, housing or grub screws, record those separately. A nominal 30 mm axle does not automatically identify the complete bearing unit.
Common kart-bearing families in the RKP range
- 6000 2RS – used in some stub-axle applications.
- 6003 2RS, 6004 2RS and 6203 2RS – common sealed-bearing references used in kart wheel and related applications.
- UC206, 30 mm bore and UC210, 50 mm bore – insert-bearing options for different axle systems.
- UCFL206 with housing and 30 mm axle bearing holder with UC206 – complete units where the housing matters as much as the insert.
- B6/30 2RS triple-grub-screw bearing – a different locking arrangement despite the same nominal axle size.
Diagnose why it failed before fitting another
SKF’s bearing failure guidance explains that damage patterns can point to the root cause. On a kart, useful evidence includes contamination, corrosion, insufficient or incorrect lubrication where applicable, incorrect mounting, misalignment, excessive preload, impact damage, a bent axle or a damaged housing.
- Keep the failed bearing instead of binning it immediately.
- Photograph both rings, seals, housing and shaft.
- Check whether the damage repeats on the same corner or axle position.
- Inspect mating parts before pressing in the replacement.
- Do not transmit fitting force through the rolling elements.
What to send RKP
- Complete bearing reference
- Bore × outside diameter × width
- Seal or shield markings
- Locking collar or grub-screw arrangement
- Housing reference and bolt spacing
- Kart model, component location and clear photographs
Primary sources
Reviewed 25 August 2026. Confirm the complete bearing specification and application before ordering.