How to Bleed & Replace Brake Fluid on a 2005 Yamaha Grizzly 660 4X4

Shop parts for a 2005 Yamaha Grizzly 660 4X4 ATV.

This guide is written exclusively for MotoSport customers and walks you stepbystep through safely flushing old brake fluid and bleeding the hydraulic brakes on a 2005 Yamaha Grizzly 660 4X4. Follow every step carefully, use quality tools and fluid, and observe safety precautions.

What you need

  • DOT 4 brake fluid (manufacturer recommends DOT 4 for the Grizzly 660)
  • Clear tubing to fit bleed nipples
  • Catch bottle for old fluid
  • Hand pump or vacuum bleeder (optional but speeds the job)
  • Flat and Phillips screwdrivers, 8-12mm wrenches for bleed nipples and banjo bolts
  • New crush washers for banjo bolts (recommended)
  • Clean rags and gloves
  • Small funnel or plastic syringe for topping reservoir
  • Torque wrench (recommended for banjo bolts when reinstalling)

Safety & prep

  • Work on a cool bike parked on stable, level ground. Use wheel chocks and a center stand or jack if needed.
  • Brake fluid damages paint & plastics. Cover painted surfaces and wipe spills immediately.
  • Always use fresh, sealed DOT 4 fluid. Do not mix with mineral or silicone fluids.
  • If the reservoir is filthy, clean the cap area before opening to prevent contamination.

Model notes for the 2005 Yamaha Grizzly 660

  • The Grizzly 660 uses hydraulic disc brakes with a handlebar master cylinder for the front brake and a footoperated rear master cylinder for the rear brake. There is no factory ABS.
  • Some Grizzly 660s develop sticky caliper pistons or corroded banjo fittings with highmileage or exposure to wet conditions. Expect to inspect calipers when you have the wheels off.
  • Brake lines and fittings can be 15+ years old on older machines — replace cracked hoses or corroded banjo bolts and use new crush washers when reassembling.
  • Recommended interval for replacing brake fluid is every 1-2 years depending on use & exposure to water; harsher use calls for more frequent service.

Overview of the process

You will replace fluid and bleed each brake circuit: front (handlebar master), rear (foot master), and calipers. Work one master cylinder at a time, keeping the reservoir topped with fresh DOT 4 fluid throughout so air cannot be drawn in.

Stepbystep procedure

1. Access & inspect

  • Locate the front master cylinder on the right handlebar and the rear master cylinder near the foot controls.
  • Clean around the caps, then remove caps and diaphragms. Keep the reservoirs as full as practical with fresh DOT 4 fluid to limit air entry.

2. Determine bleed order

Bleed the caliper farthest from its master cylinder first, then work toward the master. For the Grizzly 660 that typically means:

  • Front brake circuit: farthest caliper first (if dual front calipers, follow farthest to nearest).
  • Rear brake circuit: farthest caliper first, then the nearer.

3. Prepare bleed fittings

  • Fit clear tubing onto the bleed nipple and submerge the other end in a bottle partially filled with clean brake fluid to prevent air reentry.
  • Loosen bleed nipple slightly so you can open it when instructed (use the correct wrench to avoid rounding the nipple).

4. Bleed using the handpump or syringe (recommended)

  • Attach a vacuum pump to the bleed nipple or use the master cylinder to push fluid through. If using a vacuum pump, create steady vacuum while the lever/pedal is cycled.
  • With an assistant: Have them slowly squeeze the lever or press the pedal several times and hold it against resistance. Open the bleed nipple briefly to allow fluid and air out, then close the nipple. Instruct the assistant to release the lever/pedal only after the nipple is closed.
  • Repeat until no air bubbles are visible in the tubing and clear fluid flows. Keep topping the reservoir frequently with fresh DOT 4 to avoid drawing air into the master.

5. Bleed each caliper

  • Work in the established order. For each caliper: pump/operate the control, open the nipple to expel fluid, close nipple, then release the control. Continue until fluid is clear and bubblefree.
  • Don't let the reservoir run low at any time.

6. Flush the master cylinder and reservoir

  • If replacing all fluid, use a syringe or funnel to remove old fluid from the reservoir periodically and refill with fresh DOT 4 while bleeding to assure complete exchange.
  • Repeat bleeding passes until the fluid coming out is fresh and free of bubbles.

7. Final checks & reassembly

  • Close and tighten all bleed nipples to spec handtight plus a quarter turn; if you have torque specs, use them. Wipe any spilled fluid.
  • Replace any banjo bolts you removed with new crush washers and torque to spec. Inspect hoses and fittings for leaks.
  • Reinstall reservoir diaphragms and caps. Clean off tools and any residue.

Benchmarks for completion

  • Brake lever and pedal should feel firm and not sink to the bar or floor under steady pressure.
  • No fluid leaks at bleed nipples, banjo bolts, or hoses.
  • Clear, clean brake fluid in reservoirs; no visible contamination or moisture.

Troubleshooting

  • If lever/pedal remains spongy after thorough bleeding, suspect a hidden air pocket, damaged master cylinder seals, or internal caliper issues. Repeat bleeding and inspect components.
  • Stubborn air can be helped by elevating the master cylinder or rotating the caliper slightly to let trapped air escape while you cycle the control.
  • If calipers stick after fluid change, inspect pistons and seals for corrosion; rebuild or replace calipers as needed.

Maintenance tips

  • Use only DOT 4 and replace fluid every 1-2 years or sooner if you ride in wet/muddy conditions.
  • Keep spare crush washers and inspect brake hose condition during every fluid change.
  • After heavy riding or water crossings check brakes for contamination and rebleed if the feel changes.

Following these steps will restore braking performance on your 2005 Yamaha Grizzly 660 4X4 and help you identify worn components that should be replaced. If you encounter internal master or caliper failures, consult a qualified technician or contact MotoSport for parts and service recommendations.

Related Shopping Categories

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Shop Brake Lines for a 2005 Yamaha Grizzly 660 4X4 ATV.

Shop Brake Tools for a 2005 Yamaha Grizzly 660 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.