How to Bleed & Replace Brake Fluid on a 2017 Kymco MXU 150X
Shop parts for a 2017 KYMCO MXU150X ATV.
This MotoSport-exclusive guide walks you through a safe, clear process to replace and bleed the brake fluid on a 2017 Kymco MXU 150X. Follow these steps carefully – brakes are a critical safety system. If you're not comfortable with mechanical work, have a trained technician perform the service.
What you need
- DOT 4 brake fluid (do not mix different fluid types; DOT 3 is sometimes compatible but DOT 4 is recommended for improved boiling point)
- Clear plastic tubing that fits the bleed nipple
- Small catch bottle or jar, partially filled with new fluid to allow one-way flow
- Wrenches sized for Kymco bleed nipples (usually 8 mm or 10 mm; verify on your unit)
- Clean rags, nitrile gloves, safety glasses
- Brake cleaner and a brush to clean hardware before opening the system
- Assistant (helpful for pressure-bleeding or pedal/lever actuation)
Service notes specific to the MXU 150X
- The MXU 150X uses a compact hydraulic brake system with a handlebar-mounted master cylinder for the front/rear control (check your specific ATV layout). Locate the master cylinder reservoir near the handlebars and the bleed nipples at each caliper.
- Reservoir access may be under a small cover; clean the area thoroughly before opening to prevent contamination.
- ATV tires off the ground: stabilize the machine on a level surface and use a proper center stand or jack. Never rely on a jack alone without stands.
- Kymco recommends replacing fluid periodically; if fluid is dark or contains moisture it must be replaced. Moisture lowers boiling point – replace immediately if contaminated.
Preparation
- Park the MXU 150X on level ground, engine off, key removed. Secure with chock blocks.
- Clean the reservoir cap area and remove the cap slowly. Wipe away debris before opening to avoid contamination.
- Check current fluid level and color. If fluid is dark or cloudy, you will need a full flush and bleed.
- Add fresh DOT 4 fluid to the reservoir to the "max" line. Do not overfill.
- Identify bleed nipple locations: front calipers, rear caliper. Note which caliper is farthest from the master cylinder — that one gets bled first.
Bleeding sequence & method
Use the following method for a gravity-assisted or two-person pressure bleed. Do not introduce air by letting reservoir run dry.
Step A – One-person (squeeze/hold) or two-person pump method
- Fit clear tubing over the bleed nipple and submerge the other end in the catch bottle containing fresh fluid. The tubing should keep air out of the nipple when opened.
- Have your assistant slowly squeeze and hold the brake lever (or foot pedal if applicable) to build pressure, or if one person, use steady squeezes and hold the lever with a block.
- With the lever held, open the bleed nipple about a half turn. Fluid and air will flow into the tubing into the bottle. Close the nipple before the lever is released. Repeat until clear, bubble-free fluid comes out.
- Keep the master cylinder reservoir topped up between cycles to prevent drawing air back into the system. Never allow it to go below the minimum mark.
- Repeat this process for each caliper, working from the farthest caliper to the closest to the master cylinder. Typically: rear caliper (if farthest), then front calipers. For a left/right pair, bleed the furthest from the master cylinder first.
Step B – Gravity or pressure-bleeder alternative
If using a pressure bleeder or vacuum tool, follow the tool manufacturer instructions but maintain reservoir level and follow the same farthest-to-closest sequence. Never use air compressor pressure directly on the reservoir.
Finishing steps
- When flow from all bleed nipples is clear and free of air, tighten bleed nipples snugly. Do not overtighten; follow torque specs in the service manual if available.
- Top the reservoir to the correct level and reinstall the cap with a clean diaphragm. Wipe off any spilled fluid immediately – brake fluid damages paint and plastics.
- Operate the brake lever/pedal several times to confirm firm feel. If the lever is spongy, repeat bleeding until firm.
- Clean all fittings with brake cleaner and inspect for leaks with the ATV under light braking pressure. Recheck fluid level after a short test ride and retorque fittings if needed.
Safety & disposal
- Brake fluid is hygroscopic and corrosive. Wear gloves & eye protection and avoid skin contact. Keep fluid away from painted surfaces.
- Collect used fluid in a sealed container and dispose of it according to local hazardous-waste regulations.
Common issues & troubleshooting
- Persistent spongy lever after repeated bleeding: check master cylinder seals, brake hoses for collapse, and caliper pistons for corrosion. Replace damaged components.
- Brake drag after service: ensure caliper pistons are fully seated and hoses are not collapsed. Verify caliper sliding pins are clean and lubricated where applicable.
- Leaks from banjo bolts or bleed nipples: replace crush washers and tighten to spec; if threads are damaged, replace the component.
Perform this service every 1-2 years depending on use and storage conditions, more often for wet or heavy-use riding. For model-specific torque values and component diagrams, refer to your MXU 150X service manual or contact MotoSport parts & service for OEM components and advice.
Related Shopping Categories
Shop Brake Fluid for a 2017 KYMCO MXU150X ATV.
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Shop Brake Tools for a 2017 KYMCO MXU150X 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.