How to Bleed and Replace Brake Fluid on a 2016 Kymco MXU 450i
Shop parts for a 2016 KYMCO MXU450i ATV.
This MotoSport guide walks you through bleeding and replacing the brake fluid on a 2016 Kymco MXU 450i. Follow these steps carefully to restore firm braking performance, avoid contamination, and protect your hydraulic components.
Why and when to replace brake fluid
- Brake fluid absorbs moisture over time, lowering boiling point and causing spongy brakes.
- Replace every 1-2 years or sooner if you ride in wet conditions, deep water crossings, or notice soft lever/pedal feel.
- DOT 4 is the factory-specified type for the MXU 450i; verify your owner’s manual and always use clean, sealed fluid.
Tools & supplies
- DOT 4 brake fluid, new sealed bottle
- Wrench or socket to fit bleeder screws (usually 8mm or 10mm)
- Clear plastic tubing that fits over bleeder nipple
- Catch bottle or jar, line clamp or one-way valve (optional)
- Brake cleaner, rags, small funnel
- Torque wrench for caliper/resevoir fasteners if you remove components
- Gloves & safety glasses
Safety and prep
- Work on a level surface with the engine off and key removed.
- Protect paint and plastics from spilled fluid – brake fluid damages finish.
- Wear gloves & eye protection. Dispose of old fluid per local regulations.
- Locate the master cylinder reservoir on the handlebar (front) or near the rear brake pedal for the rear circuit. MXU 450i uses separate circuits for front & rear.
Overview of the MXU 450i brake system notes
- 2016 MXU 450i typically has dual front calipers and a single rear caliper. Bleed procedures are conventional – start furthest from the master cylinder and work toward it.
- Front master cylinder services both front calipers; rear circuit is separate. Confirm which reservoir feeds which caliper before starting.
- Bleeder screw location: front calipers on the outside of the rotor area; rear caliper on the driveline side. Use good lighting and a mirror if needed.
- Some owners report tight bleeder screws on older MXUs – seize-prone. Apply penetrating lube sparingly and use correct wrench size to avoid rounding.
Step-by-step brake fluid replacement
1. Inspect and prepare
- Clean around reservoirs and bleeder screws with brake cleaner to prevent dirt entering the system.
- Remove reservoir caps and diaphragms carefully. Keep the reservoir top as clean as possible.
2. Top up with fresh fluid
- Pour DOT 4 fluid into the reservoir until it reaches the max mark. Replace fluid cap loosely to reduce contamination risk while you bleed.
3. Bleeding order
- Front brakes: start with the caliper furthest from the master cylinder. For the MXU 450i that is usually the right front, then left front.
- Rear brake: bleed after the front circuit is complete.
4. Manual push-bleed method (recommended for one helper)
- Attach clear tubing to the bleeder nipple and route tubing into a catch bottle partially filled with fresh fluid to avoid air return.
- Have an assistant apply steady pressure to the brake lever or pedal but don’t hold it fully compressed.
- Open the bleeder screw 1/4 to 1/2 turn. Observe fluid & air bubbles flowing into the tube. Close the screw before the assistant releases the lever/pedal.
- Repeat until only clean fluid without air bubbles flows and the fluid level in the reservoir remains stable. Keep reservoir topped up during the process.
5. Vacuum or pressure bleed alternative
- If using a hand vacuum or pressure bleeder, follow the tool manufacturer instructions. Still follow the correct bleed order and keep reservoir level full to avoid sucking air in.
6. Final checks
- Tighten bleeder screws to factory torque, wipe any spilled fluid, and reinstall reservoir caps securely.
- Test lever and pedal feel with the machine supported so wheels are off the ground; brakes should feel firm without sinking.
- Do a low-speed functional test in a safe area to confirm stopping performance before normal use.
Troubleshooting
- Persistent spongy brakes after thorough bleeding often indicate internal master cylinder or caliper seals worn — replace the faulty component.
- If one caliper never clears air, check for collapsed brake hose or stuck caliper piston; replace as needed.
- Leaking bleeder screws or stripped threads require caliper service or replacement; avoid over-tightening.
Maintenance tips specific to the 2016 Kymco MXU 450i
- Check brake hose routing and clips after any off-road use; MXU owners often encounter snagged lines during trail riding.
- Inspect brake pads and rotor thickness when you bleed fluid – many MXU 450i owners run aggressive terrains that accelerate pad wear.
- Store DOT 4 in a cool, sealed place and discard any fluid bottle left open for more than a few months to avoid moisture absorption.
- Because the MXU 450i is often used for utility work, check for contamination from hydraulic oil or water in the reservoir if you see discolored fluid – contamination may require caliper overhaul.
Parts & replacement components
- When replacing components, choose OEM-spec calipers, master cylinder rebuild kits, new banjo bolts with crush washers, and DOT 4 fluid.
- For reliability, replace old copper crush washers whenever you remove the banjo bolt from the caliper.
Following this MotoSport procedure will keep your MXU 450i braking safe and responsive. If you encounter worn master or caliper components, consult a MotoSport technician or your local dealer for parts and service options.
Related Shopping Categories
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Shop Brake Tools for a 2016 KYMCO MXU450i 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.