How to Bleed and Replace Brake Fluid on a 2011 Yamaha BigBear 400 4X4

Shop parts for a 2011 Yamaha BigBear 400 4X4 ATV.

This MotoSport-exclusive guide walks you through draining, flushing, and bleeding the hydraulic brake system on a 2011 Yamaha BigBear 400 4X4. Follow these steps to restore firm braking performance and maintain safe operation of your ATV. Read all steps before beginning and gather tools and materials listed below.

What you need

  • DOT 3 or DOT 4 brake fluid (check reservoir cap for spec; Yamaha typically calls for DOT 3/DOT 4 compatible fluid)
  • Clear plastic tubing that fits bleed nipple snugly
  • Catch bottle for old fluid
  • Wrench for bleed nipple (usually 8mm or 10mm)
  • Syringe or turkey baster to extract fluid from reservoir
  • Brake cleaner, shop rags, gloves, eye protection
  • Torque wrench for caliper mounting hardware if removed

Model-specific notes for the 2011 Yamaha BigBear 400 4X4

  • The BigBear 400 uses a simple hydraulic system with front dual calipers & a rear caliper; the reservoir is located on the handlebars. Use DOT 3 or DOT 4 only — do not use DOT 5 (silicone).
  • Stock ABS is not present on this model; bleeding is straightforward and manual per wheel caliper.
  • The master cylinder on the handlebar is compact; avoid overfilling the reservoir because fluid spills can damage plastics and seats.
  • If the system has been contaminated with water or shows brown/black fluid, a full flush is recommended rather than partial topping off.
  • Replace rubber hoses if they are cracked or swollen; aged hoses can trap moisture and degrade braking performance.

Preparation

  1. Park ATV on level ground, engage parking brake (if equipped), and secure with a block or lift so wheels can be worked safely.
  2. Remove seat and any panels necessary to access the rear caliper if required. Keep a clean workspace.
  3. Clean around reservoir cap thoroughly to prevent dirt entering system when opened.
  4. Put on gloves & eye protection.

Step 1 – Remove old fluid from reservoir

  1. Open reservoir cap and remove diaphragm/foam insert carefully; set parts on a clean rag.
  2. Use syringe or turkey baster to extract as much old fluid as possible from reservoir. Dispose of used fluid properly.
  3. Wipe inside of reservoir with a lint-free rag if contaminated. Do not introduce solvent into reservoir.
  4. Refill reservoir with fresh brake fluid to the MAX level mark.

Step 2 – Bleed order & method

Bleed starting with the wheel furthest from the master cylinder and proceed to the closest. On the BigBear 400 this commonly means:

  • 1st: Rear caliper
  • 2nd: Right front caliper
  • 3rd: Left front caliper

Use the gravity, pressure, or two-person pedal (lever) method. MotoSport recommends a two-person method for fastest, most reliable results: one operator to actuate the brake lever/pedal and one to open/close the bleed nipple.

Step 3 – Two-person bleeding procedure

  1. Attach clear tubing to bleed nipple and place other end into a catch bottle partially filled with a little fresh fluid to prevent air re-entry.
  2. Have the helper slowly pull the brake lever or press the pedal several times and hold it in the applied position.
  3. Open the bleed nipple about a quarter turn to allow fluid/air to flow into the tubing. Close the nipple before the helper releases the lever/pedal.
  4. Repeat: pump lever/pedal, hold, open nipple, close nipple, release lever. Continue until you see clear, bubble-free fluid and no air in the tubing.
  5. Keep the master reservoir topped up throughout to prevent air ingestion. Never let the reservoir run dry.
  6. Tighten the bleed nipple to spec (hand tight plus a small quarter-turn) and wipe away any spilled fluid immediately with a rag and brake cleaner.

Step 4 – Full system flush (if needed)

  1. If fluid is heavily discolored or contaminated, repeat bleeding cycles until clean fluid appears, replacing reservoir fluid multiple times if necessary.
  2. For a complete flush, tighten all bleed nipples, remove a hose at caliper if accessible, and push fresh fluid through from the master cylinder using a syringe or hand pump while the open caliper drain directs old fluid into a catch container. Reattach and bleed normally after flushing.

Step 5 – Final checks

  1. Ensure reservoir is filled to the MAX line and reinstall diaphragm and cap securely.
  2. Verify bleed nipples are tightened and caliper bolts are torqued to factory spec if disturbed.
  3. Operate the brake lever/pedal several times to confirm a firm, consistent feel. If soft or spongy, additional bleeding or inspection for leaks/air is required.
  4. Check for leaks around calipers, lines, fittings, and master cylinder after a short test ride at low speed.

Maintenance tips & troubleshooting

  • Replace brake hoses every 5-7 years or sooner if cracked; OEM or high-quality braided lines improve firmness and longevity.
  • If you repeatedly get air back into the system, inspect for cracked hose ends, loose fittings, or a leaking master cylinder seal.
  • Store brake fluid in a sealed container; it absorbs moisture from air, which reduces boiling point and degrades braking performance.
  • Dispose of old brake fluid following local hazardous-waste regulations; do not pour down drains.

Common parts & replacements for the BigBear 400

  • Brake pads (front & rear)
  • Brake hoses
  • Master cylinder repair kit (seals & diaphragms)
  • Bleed nipples & washers

Follow this guide for reliable brake-fluid replacement and bleeding on your 2011 Yamaha BigBear 400 4X4. If you encounter persistent issues, consult a qualified ATV technician or contact MotoSport for parts and expert help.

Related Shopping Categories

Shop Brake Fluid for a 2011 Yamaha BigBear 400 4X4 ATV.

Shop Brake Bleeders for a 2011 Yamaha BigBear 400 4X4 ATV.

Shop Brake Pads for a 2011 Yamaha BigBear 400 4X4 ATV.

Shop Brake Lines for a 2011 Yamaha BigBear 400 4X4 ATV.

Shop Brake Tools for a 2011 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.