How to Bleed and Replace Brake Fluid on a 2018 Kymco MXU 500i
Shop parts for a 2018 Kymco MXU 500i ATV.
This MotoSport-exclusive guide walks you through safely flushing and bleeding the hydraulic brake system on a 2018 Kymco MXU 500i. Follow each step, use the recommended materials, and check model-specific notes at the end.
What you need
- DOT 4 brake fluid (do not mix with DOT 5)
- Clear 1/4" vinyl tubing
- Brake bleeder bottle or clean catch container
- Wrenches for bleeder nipples (usually 8mm or 10mm)
- Socket set and screwdrivers to access master cylinder and calipers
- Disposable gloves, safety glasses, rags
- Turkey baster or fluid syringe (to remove old fluid from reservoir)
- Torque wrench (for caliper bolts if removed)
- Helper for pedal-pump or lever-pull method, or vacuum/pressure bleeder
Safety and prep
- Work on a level surface with the engine off and key removed.
- Park the MXU securely with wheels chocked.
- Brake fluid damages paint & plastics – protect bodywork and clean spills immediately.
- Do not allow air to enter the master cylinder reservoir for longer than necessary.
Identify components
- Master cylinder & reservoir: located near the handlebars for the front, with a separate reservoir or integrated system for rear depending on configuration.
- Calipers and bleeder nipples: at each wheel where the hydraulic line meets the caliper.
Bleed order
Use the standard furthest-to-closest sequence relative to the master cylinder. For the MXU 500i that sequence typically is:
- Rear right (furthest)
- Rear left
- Front right
- Front left (closest)
Step-by-step flush & bleed
- Remove reservoir cap and diaphragm. Suck out old fluid with a turkey baster until level is low but not empty.
- Fill reservoir with fresh DOT 4 fluid. Keep the cap off but reservoir covered to prevent contamination.
- Start at the furthest wheel. Slip clear tubing over the bleeder nipple and place the other end into a catch bottle partially filled with fresh fluid to prevent air backflow.
- Loosen the bleeder nipple a quarter to half turn. If using a helper: have them slowly pull the brake lever (or press the pedal) to apply steady pressure and hold. Open the bleeder nipple so fluid & air escape, then close the nipple before the lever/pedal is released. Repeat until only clean fluid with no air bubbles flows.
- If using a vacuum or pressure bleeder: attach device, pump/supply per tool instructions, and open the nipple until clear fluid flows. Maintain reservoir level above the minimum during the process.
- Keep reservoir topped with fresh fluid throughout to prevent introducing air into the master cylinder.
- Once the line is clear, tighten the bleeder nipple while fluid pressure is not being applied. Wipe any spilled fluid and move to the next wheel in the sequence.
- After all four calipers are bled, perform several steady lever/pedal applications to confirm a firm feel. Check reservoir fluid level and top to the specified mark, then reinstall the cap and diaphragm.
- Test brakes at low speed in a safe area before riding normally. Recheck bleeder nipples and reservoir for leaks.
Notes on technique
- Always close the bleeder before releasing the lever to avoid drawing air back into the system.
- If excessive air persists, consider bench-bleeding the master cylinder or repeating the process with a pressure/vacuum bleeder.
- Do not reuse old fluid or mix DOT 4 with DOT 5 (silicone). If in doubt, flush the entire system.
- Dispose of used brake fluid at a proper recycling facility.
Model-specific notes for the 2018 Kymco MXU 500i
- The MXU 500i uses DOT 4 brake fluid as factory service recommends; confirm by checking the reservoir cap marking before starting.
- Some 2018 MXU 500i variants have a combined master cylinder for front/rear with proportioning built into the system; maintain reservoir level carefully to avoid uneven pressure during bleeding.
- Caliper access can be restricted by carrier or skid plates on utility builds – remove obstructing hardware to reach bleeders safely.
- If your MXU has an ABS or electronic brake-assist option, follow service manual procedures for ABS-compatible bleeding; many aftermarket DIY methods may not address ABS modules properly. If unsure, consult a dealer or MotoSport service resource.
- Aftermarket heavy-duty brake lines are common upgrades for utility use; if your ATV has braided lines, inspect fittings for corrosion and torque per manufacturer spec when reassembling.
- Check master cylinder diaphragm condition & reservoir vent path – a clogged vent can mimic air in the system.
Troubleshooting
- Spongy lever after bleeding: repeat bleeding, check for leaks, inspect caliper pistons for corrosion or seized movement.
- Brake drag after bleeding: ensure bleeder nipples are tightened properly, caliper pistons have retracted, and hoses are not collapsed.
- Persistent air: bench-bleed master cylinder and use pressure/vacuum bleeder for higher reliability.
Maintenance interval
Inspect brake fluid annually and replace every 1-2 years or sooner with heavy use in wet/muddy conditions. Fresh fluid preserves braking performance and protects internal components.
For MotoSport-quality replacement parts and Kymco-specific components, use the official parts link above to find compatible master cylinder kits, caliper hardware, bleeder screws, lines, and DOT 4 fluid for your MXU 500i.
Related Shopping Categories
Shop Brake Fluid for a 2018 Kymco MXU 500i ATV.
Shop Brake Bleeders for a 2018 Kymco MXU 500i ATV.
Shop Brake Pads for a 2018 Kymco MXU 500i ATV.
Shop Brake Lines for a 2018 Kymco MXU 500i ATV.
Shop Brake Tools for a 2018 Kymco MXU 500i ATV.
Disclaimer: This guide is provided for general informational purposes only and is not intended to replace your motorcycle's official owner's manual. Always refer to your manufacturer's documentation for model-specific instructions, torque specifications, safety procedures, and maintenance requirements. If you are unsure or inexperienced, consider seeking assistance from a qualified mechanic or technician.