How to bleed and replace brake fluid on a 2010 Yamaha Bigbear 400 4X4
Shop parts for a 2010 Yamaha Bigbear 400 4X4 ATV.
This MotoSport proprietary guide walks you through a complete brake fluid change and bleed on a 2010 Yamaha Bigbear 400 4X4. Follow each step carefully, use clean tools and new brake fluid, and work methodically to avoid air in the lines. If you are not comfortable with brake work, have a qualified mechanic complete the job.
What you need
- DOT 4 brake fluid (Yamaha specification). Use fresh, unopened fluid and never mix with contaminated fluid.
- Clear plastic tubing that fits snugly over bleed nipples
- Small catch bottle or jar
- Wrenches to fit bleed nipples (usually 8mm or 10mm)
- Screwdriver or 1/4" driver for reservoir caps
- Clean rags, latex gloves, and eye protection
- Brake cleaner and a small brush for caliper clean-up
- Torque wrench for any caliper or reservoir hardware you remove
- Assistant (recommended) or a one-man vacuum or pressure bleeder
Model notes for the 2010 Yamaha Bigbear 400 4X4
- Brake system layout: handlebar master cylinder(s) for the front and a rear master cylinder actuated by the foot pedal. Bleed nipples are located on the calipers. Confirm which caliper corresponds to each master cylinder before starting.
- Recommended fluid: Yamaha generally calls for DOT 4 in this model. Use only the specified DOT fluid and keep the reservoir sealed to avoid moisture absorption.
- Parking and support: park on level ground, block wheels, and use a center-stand or jack stands rated for ATVs. Never rely on the ATV jack alone while working on the brakes.
- Corrosion & seals: the Bigbear can see off-road moisture and mud. Inspect lines, banjo bolts, copper washers, and caliper pistons for corrosion or hardened seals when you open the system.
- Caliper removal: if pads are seized or pistons are corroded, you may need to remove calipers for cleaning or rebuild kits. Keep torque values as specified in the service manual when reassembling.
Preparation
- Wear gloves and eye protection. Brake fluid damages paint & plastics; protect surfaces with rags or plastic sheeting.
- Clean reservoirs and caps before opening to prevent contamination.
- Position a drip tray under each caliper bleed nipple you will open.
- Open the front and rear reservoirs and top off with new DOT 4 brake fluid so they start full.
- Keep the reservoir caps loosely in place while working to minimize contamination but allow fluid level inspection.
Bleed order
Bleed from the furthest caliper to the closest relative to each master cylinder. Typical order for Bigbear 4X4:
- Right front caliper
- Left front caliper
- Rear caliper(s)
Standard two-person bleed method
- Attach clear tubing to the bleed nipple and place the other end in a jar partially filled with new fluid to prevent air re-entry.
- Have your assistant sit on the ATV to apply normal brake force (safely supported) or hold the lever/pedal at a consistent pressure as you cycle the systemalternatively use a one-man vacuum or pressure bleeder.
- With tubing attached, crack the bleed nipple about a half-turn. Ask the assistant to gently squeeze the lever or press the pedal until the bore is near the end of its travel, then hold it there.
- Tighten the bleed nipple while the lever/pedal is held. Release the lever/pedal slowly. This prevents air being drawn back in.
- Repeat until you see clear fluid with no bubbles in the tubing, topping off the reservoir frequently to keep it above the minimum level.
- Close the bleed nipple, wipe away fluid, and move to the next caliper in the sequence.
One-person vacuum or pressure bleed method
- Follow the device manufacturer instructions. Use the same furthest-to-closest sequence.
- Maintain reservoir level — do not let it run dry while vacuuming/pressurizing.
Flushing the entire system
- If fluid is dark or contaminated, continue bleeding until fresh clear fluid flows from each bleed nipple. Replace the reservoir fluid several times if necessary.
- Work methodically and do not mix old and new fluid in the reservoir when doing final fills.
Final checks and reassembly
- After bleeding all wheels, verify reservoir levels are at the proper mark and secure reservoir caps.
- Cycle each lever/pedal several times to verify firm feel and normal travel. If spongy, repeat bleeding steps.
- Inspect for leaks at bleed nipples, banjo fittings, and master cylinder connections. Replace copper crush washers on banjo bolts if removed.
- Clean any spilled fluid and wash affected painted surfaces with water immediately, then dry.
- Torque any caliper or banjo bolts to Yamaha specified values (refer to the service manual for exact numbers) and recheck after a short test ride.
Test ride and safety
- Perform a slow, controlled test in a safe area to confirm braking performance before normal riding.
- Recheck fluid level and hardware after the first short ride and periodically for the next few rides.
Maintenance tips for the Bigbear 400
- Change brake fluid every 1-2 years or sooner if you ride in wet/muddy conditions. Brake fluid is hygroscopic and will degrade braking performance over time.
- Inspect brake lines for cracking or chafing at steering and suspension pivots specific to the Bigbear layout.
- Carry spare crush washers for banjo fittings and a small container of DOT 4 fluid on longer trips.
- After heavy off-road use, inspect calipers and pistons for grit. Clean and lubricate sliding surfaces with brake-safe grease.
If you encounter seized pistons, persistent air, or damaged lines, stop and source replacement parts or professional service. Properly bled and maintained brakes are critical to safe riding on the Bigbear 400.
Related Shopping Categories
Shop Brake Fluid for a 2010 Yamaha Bigbear 400 4X4 ATV.
Shop Brake Bleeders for a 2010 Yamaha Bigbear 400 4X4 ATV.
Shop Brake Pads for a 2010 Yamaha Bigbear 400 4X4 ATV.
Shop Brake Lines for a 2010 Yamaha Bigbear 400 4X4 ATV.
Shop Brake Tools for a 2010 Yamaha Bigbear 400 4X4 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.