KuKirin G2 and G4 are among the most common scooters we help owners upgrade with XOD H-Series hydraulic brakes. They look similar from a brake-upgrade perspective, but several details matter: caliper direction, front rotor spacing, mounting hardware and the brake-sensor connector.
This guide has been updated after our hands-on test of the KuKirin G2 2026. The newer G2 now uses 160mm rotors front and rear, but it still uses the same XOD caliper combination as the earlier G2: H880 front and H800 rear.
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Old G2 vs G2 2026 Older G2 setup G2 2026 setup Bracket difference G4 setup Sensor adapter 4mm spacer FAQKuKirin G2: Older Version vs G2 2026
The biggest brake-hardware difference between the two G2 generations is rotor size.
You do not need to purchase a different brake rotor for either G2 generation. The older G2 keeps its original 140mm rotors, while the G2 2026 keeps its original 160mm rotors.
For the detailed hands-on 2026 test, read our KuKirin G2 2026 XOD Hydraulic Brake Fitment Test.
Older KuKirin G2: XOD Hydraulic Brake Setup
The earlier KuKirin G2 uses 1.9mm × 140mm rotors on both wheels. These original rotors can remain on the scooter during the XOD upgrade.
The front wheel requires a 4mm rotor spacer between the hub and brake rotor. The rear wheel does not require an additional 4mm spacer.
Use the bracket supplied with the XOD hydraulic brake, together with the original KuKirin caliper bolts and original metal washers.
This bracket setup is specific to the older G2. Do not automatically copy it to the G2 2026.
KuKirin G2 2026: What Changed?
The updated G2 uses larger 1.9mm × 160mm brake rotors on both the front and rear wheels.
Our real 2026 installation confirmed that the XOD caliper combination itself remains unchanged:
- Front: XOD H880
- Rear: XOD H800
- Front: original 160mm rotor + 4mm spacer
- Rear: original 160mm rotor, no additional 4mm spacer
The move from 140mm to 160mm rotors does not require changing to a different XOD H-Series combination. The tested G2 2026 still uses H880 front and H800 rear.
⚠️ Critical G2 Difference: The Caliper Bracket Setup Changed
This is the most important detail to understand if you have previously installed XOD brakes on an older G2.
Use the XOD-supplied caliper bracket.
Reuse the original KuKirin bolts and metal washers.
Do not use the XOD-supplied bracket.
Reuse the original KuKirin bracket, bolts and metal washers.
The front washers go between the XOD caliper and the original bracket.
The two generations use the same H880/H800 caliper combination, but they do not use the same mounting-bracket arrangement.
KuKirin G2 Front Wheel: Why the 4mm Rotor Spacer Is Still Needed
XOD hydraulic calipers are wider than the original G2 mechanical calipers. On both G2 generations, the front rotor needs additional outward offset to create enough caliper clearance.
Use the 4mm version of the 44mm BCD 6-bolt rotor spacer between the front hub and brake rotor.
The G2 rear wheel does not require an additional 4mm rotor spacer in our established XOD fitment.
KuKirin G2 Front-Wheel Metal Spacer Position
The rotor spacer and axle metal spacer are two different parts. Do not confuse them.
On the G2 front wheel, one of the original metal spacers around the axle must be positioned correctly so the brake-disc mounting screws do not rub against the frame.
KuKirin G4: Keep the Original Bracket, Bolts and Washers
The G4 does not use the same front-spacer solution as the G2. The key installation detail is preserving the original mounting hardware.
- Keep the original KuKirin G4 caliper bracket.
- Keep the original mounting bolts.
- Keep all original metal washers.
- Reuse the washers when centering the XOD hydraulic caliper over the rotor.
The original mounting hardware helps position the replacement hydraulic caliper correctly. Before final tightening, spin the wheel by hand and check rotor clearance.
Why KuKirin G2 and G4 Need a Dedicated Brake-Sensor Adapter
The XOD H-Series brake lever includes a motor power-off sensor. G2 and G4 use a different display-side connection from the standard 2-pin interface found on many other compatible scooters.
There are two ways to solve this:
Installation Checks Before Riding
The pistons can move too far outward and create a hydraulic-service problem.
After installation:
- Spin each wheel by hand.
- Check that the rotor passes through the caliper without severe interference.
- Confirm all bolts and washers are in their correct positions.
- Check the brake-sensor motor cut-off function.
- Test lever feel.
- Perform a controlled low-speed brake test before normal riding.
In our G2 2026 test, a slight pad/rotor rubbing sound gradually reduced after about 5 km as the new pads bedded in. Severe rubbing or poor wheel rotation is not something to ignore; recheck the installation instead.
Maintenance & Further Installation Help
Hydraulic brakes still need routine inspection. Check pad thickness, rotor condition, hose connections and lever feel regularly.
- XOD Replacement Brake Pads
- XOD Hydraulic Brake Installation & User Manual
- How to Bleed XOD Hydraulic Brakes
- How to Shorten XOD Hydraulic Brake Hose
- KuKirin G2 2026 Real Fitment Test
If your scooter version or brake layout is unclear, send clear photos of the front wheel, rear wheel and original brake-lever connector to service@xodbrakes.com before ordering.
KuKirin G2 & G4 XOD Hydraulic Brake FAQ
Which XOD brakes fit the KuKirin G2?
Both the older G2 and the G2 2026 use XOD H880 at the front and H800 at the rear in our established fitment.
Does the older KuKirin G2 need a replacement brake rotor?
No. The older G2 already uses 1.9mm × 140mm brake rotors front and rear. Keep the original rotors and install the required 4mm spacer on the front wheel only.
Does the KuKirin G2 2026 need replacement rotors?
No. Our G2 2026 test retained the original 1.9mm × 160mm front and rear rotors.
Does the KuKirin G2 need a 4mm rotor spacer?
Yes, on the front wheel only. The rear wheel does not require the additional 4mm rotor spacer in our XOD setup.
Do the older G2 and G2 2026 use the same caliper bracket?
No. The older G2 uses the XOD-supplied bracket with the original KuKirin bolts and washers. The G2 2026 reuses the original KuKirin bracket, bolts and washers and does not use the XOD-supplied bracket.
Where do the metal washers go on the G2 2026 front caliper?
For the tested 2026 front installation, the original metal washers sit between the XOD H880 caliper and the original KuKirin bracket.
Do KuKirin G2 and G4 require a brake-sensor adapter?
Yes. The dedicated adapter is the simplest way to connect the XOD brake-lever motor cut-off sensor to the G2 or G4 wiring without modifying the new sensor cable.
Can I reuse the original G4 washers?
Yes. Keep the original G4 bracket, bolts and metal washers and use them during caliper alignment rather than discarding them.
Final Fitment Summary
H880 front + H800 rear · original 140mm rotors · 4mm front spacer · XOD-supplied caliper bracket · original KuKirin bolts and washers · dedicated sensor adapter.
H880 front + H800 rear · original 160mm rotors · 4mm front spacer · original KuKirin bracket, bolts and washers · washers between front caliper and bracket · dedicated sensor adapter.
Retain the original mounting bracket, bolts and metal washers and use the dedicated G2/G4 brake-sensor adapter when connecting the XOD brake lever.
Send your scooter model and clear brake photos to service@xodbrakes.com before ordering.