How to Bleed & Replace Brake Fluid on a 2004 Yamaha Bear Tracker

Shop parts for a 2004 Yamaha Bear Tracker ATV.

This stepbystep MotoSport guide covers safely flushing, replacing, and bleeding the hydraulic brake system on a 2004 Yamaha Bear Tracker. Follow these instructions carefully, use quality parts and fluid, and always work on a cool machine in a clean, welllit area.

Tools & supplies

  • DOT 3 or DOT 4 brake fluid (Yamaha permits DOT 3 or DOT 4; do not mix with silicone-based fluids)
  • Clear vinyl tubing that fits snugly on bleed nipples
  • Brake fluid catch bottle or container
  • Wrenches for bleed nipple size (typically 8 mm on many ATVs)
  • Turkey baster or fluid syringe for removing old fluid from reservoir
  • Clean rags and isopropyl alcohol for cleaning
  • Latex or nitrile gloves and eye protection
  • Bike stand or ramp to lift wheels off the ground
  • Optional: vacuum or pressure bleeder for faster, cleaner bleeding

Safety & preparation

  • Brake fluid damages paint and plastics — protect bodywork and immediately wipe any spills with a rag and isopropyl alcohol.
  • Work on a level surface with the ATV secured. Chock wheels if not lifting.
  • Never reuse drained brake fluid; dispose of old fluid responsibly.

Model notes for the 2004 Yamaha Bear Tracker (MMY)

  • The 2004 Bear Tracker is a lightweight utility ATV with a simple hydraulic braking system — no ABS or electronic aids to complicate bleeding.
  • Front brakes are hydraulic discs with bleed nipples on the calipers; the rear is typically hydraulic (check your specific model for caliper vs. drum). Locate the master cylinder reservoir near the handlebars or rear brake pedal master cylinder depending on which circuit you service.
  • Because the Bear Tracker is used for work and trail duty, check flexible brake hoses for cracking or swelling; replace any aged hoses before bleeding to avoid introducing air later.
  • If brake calipers or pistons are sticky after a fluid change, clean and service them or rebuild with new seals and boots to avoid premature wear of pads and rotors.

Step 1 – Inspect system

  1. Check reservoir level and condition of fluid. If fluid is dark or contaminated, full replacement is required.
  2. Inspect lines, hoses, calipers, and pads for leaks, damage, contamination, or excessive wear.

Step 2 – Remove old fluid from reservoir

  1. Use a turkey baster or syringe to remove as much old fluid from the master cylinder reservoir as possible without letting dirt fall in.
  2. Fill the reservoir with fresh DOT 3 or DOT 4 fluid to the specified level. Keep the cap loosely on between operations to reduce contamination but allow overflow to escape to a rag if needed.

Step 3 – Bleed order & approach

Bleed the brake circuit from the caliper furthest from the master cylinder first and finish with the closest. For most Bear Tracker setups: right front, left front, then rear (confirm routing on your machine).

Step 4 – Manual (twoperson) bleeding

  1. Have an assistant sit on the ATV and slowly pump the brake lever/pedal several times and hold pressure.
  2. Open the bleed nipple about a quarter turn, allow fluid & air to flow into the clear tubing into a catch bottle, then close the nipple before the assistant releases the lever/pedal.
  3. Repeat: assistant pumps & holds, you open and close nipple, until clear fluid with no bubbles flows out.
  4. Keep reservoir topped with fresh fluid between cycles; never let reservoir run dry or more air will enter the system.

Step 5 – Oneperson vacuum or pressure bleeding (recommended if alone)

  1. Attach your vacuum bleeder to the bleed nipple or pressurize the master cylinder reservoir with a pressure bleeder per the tool manufacturer instructions.
  2. Operate tool until fluid runs clear and bubblefree, topping reservoir as needed.
  3. Close bleed nipple while maintaining vacuum/pressure, then remove tool.

Step 6 – Finishing each caliper

  1. After each caliper bleeds clear, tighten the bleed nipple to spec to prevent leaks. Wipe area clean.
  2. Check lever/pedal firmness after bleeding each wheel. It should feel firm and consistent with no sponginess.

Step 7 – Replace all fluid & final checks

  1. Once all circuits are bled, top the reservoir to the correct level and reinstall cap securely.
  2. Clean any spilled fluid from paint and plastics immediately.
  3. Pump the brake lever/pedal several times to confirm firmness. If spongy, repeat bleeding process.
  4. Road/test: perform lowspeed brake checks in a safe area to confirm function before riding at speed or carrying loads.

Maintenance tips & common issues

  • Brake fluid absorbs moisture over time; replace fluid every 1-2 years depending on use and environment.
  • If brake pads or rotors smell of burned fluid or pads are soaked with fluid from a leak, replace pads and clean or replace rotors as needed.
  • If you see persistent air ingress after bleeding, inspect and replace the master cylinder cap diaphragm, reservoir cap seal, or cracked hoses.
  • Use only fresh, unopened brake fluid. Do not mix different brands with unknown histories, and keep caps on bottles when not in use.

Troubleshooting quick reference

  • Spongy lever after bleeding: likely residual air — repeat bleeding starting with furthest caliper.
  • Lever goes to handlebar or pedal bottoms out: inspect for leaks and replace damaged components; do not ride.
  • Contaminated pads/rotors: replace pads and clean or replace rotors; contaminated pads cannot be trusted.

Following this MotoSport procedure will keep your 2004 Yamaha Bear Tracker’s brakes responsive and safe. If you encounter seized calipers, deteriorated hoses, or persistent leaks, replace the defective parts rather than repeatedly bleeding a compromised system.

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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.