How to Bleed & Replace Brake Fluid on a 2009 Yamaha Wolverine 450

Shop parts for a 2009 Yamaha Wolverine 450 ATV.

This step-by-step guide, proprietary to MotoSport, walks you through safely flushing and refilling the brake system on a 2009 Yamaha Wolverine 450 (WOLV450). The Wolverine 450 uses hydraulic disc brakes with a handlebar master cylinder for the front brakes and a foot master cylinder for the rear brake. Use DOT 4 brake fluid (DOT 3 is compatible in emergencies, but DOT 4 is recommended for heat resistance). Work one hydraulic circuit at a time and keep contaminants away from all braking surfaces.

Tools & Supplies

  • DOT 4 brake fluid (new, unopened)
  • Clear plastic tubing to fit bleeder nipples
  • Small catch bottle or jar (label for used fluid)
  • Wrenches for bleeder nipples (typically 8mm or 10mm)
  • Phillips & flat screwdrivers, pliers
  • Turkey baster or fluid siphon
  • Clean rags, shop towels, brake cleaner
  • Jack or stands to stabilize machine if needed
  • Latex or nitrile gloves, eye protection

Safety & Prep

  • Work on a cool bike; do not let brake fluid contact painted surfaces – it will damage paint. Cover nearby paint with rags if needed.
  • Park on level ground, secure the ATV, and block wheels so it cannot move.
  • Wear eye protection & gloves. Keep new brake fluid sealed until use.
  • Familiarize yourself with master cylinder reservoirs: handlebar (front) and foot (rear). Treat each as a separate bleed job.

Step 1 – Remove Old Fluid From Reservoir

  1. Clean the reservoir caps & surrounding area thoroughly to prevent dirt entering the system.
  2. Open the reservoir cap and diaphragm. Use a turkey baster or siphon to remove as much old fluid as possible from each reservoir.
  3. Wipe the inside clean with a lint-free rag. Do not reuse the rag if contaminated with old fluid.
  4. Refill the reservoir with fresh DOT 4 fluid to the full mark, then close the cap lightly until ready to bleed.

Step 2 – Bleeding Order & Principle

Bleed each circuit separately. For the Wolverine 450, a reliable order is: rear circuit first (foot master cylinder) then the front circuit (handlebar master cylinder). For the front, bleed the caliper farthest from the master cylinder first if you can determine distance — typically right front then left front on most setups. Always keep the reservoir topped up during the process to prevent air re-entry.

Step 3 – Manual (Assistant) Bleeding Method

  1. Attach clear tubing to the bleeder nipple on the caliper and route into your catch bottle partially filled with a small amount of fresh fluid to prevent sucking air back.
  2. Open the bleeder nipple about 1/4 turn with the wrench. Have an assistant slowly depress the lever (or pedal) and hold it down.
  3. While held, open the bleeder to allow fluid and air to flow into the tube until flow slows. Close the bleeder nipple.
  4. Release the lever/pedal. Repeat pump — open & close — until fluid runs clear and free of bubbles. Keep reservoir filled between cycles.
  5. Once clear, tighten the bleeder nipple to snug (do not over-torque). Wipe any spilled fluid immediately.
  6. Repeat for each caliper in the specified order.

Step 4 – One-Person Squeeze-Bulb or Vacuum Method (Optional)

If working alone use a squeeze-bulb kit or a small vacuum pump on the bleeder nipple. Follow the kit instructions — keep reservoir topped, open bleeder, draw fluid until clear, close bleeder, then release vacuum. Confirm pedal/lever firmness after bleeding.

Step 5 – Benchmarks & Testing

  • Properly bled brakes produce a firm lever or pedal with minimal travel. If lever is spongy, repeat bleeding cycle.
  • Check for leaks at bleeder nipples, hose fittings, caliper seals, and master cylinder boots.
  • After bleeding both circuits, clean reservoirs, reinstall diaphragms and caps, and torque any master-cylinder fasteners to MotoSport-recommended or factory specs.
  • Lower the ATV, test brakes at very low speed in a safe area before normal riding.

Disposal

Used brake fluid is hazardous. Store in a sealed container and dispose of it according to local hazardous waste regulations. Do not pour down drains or into the environment.

Model-Specific Notes for the 2009 Yamaha Wolverine 450 Owner

  • The Wolverine 450 uses separate master reservoirs for front & rear, so bleed each master separately to avoid cross-contamination and to ensure correct pressure balance.
  • Some 2009 models show light corrosion risk if left in wet storage; inspect caliper bolts, banjo fittings and bleeder nipples for surface corrosion — replace corroded hardware to prevent leaks.
  • Factory rubber lines age and harden; if the lines are original and over a decade old, consider replacing them with DOT 4-rated stainless braided hoses for improved feel and longevity.
  • Handlebar master cylinder boots can trap water & dirt; clean and inspect boots when opening the reservoir to avoid contamination entering the system.
  • Brake pads and rotors on older Wolverines can be near end of life depending on hours; inspect pad thickness and rotor condition while bleeding. Replace worn pads before expecting optimal braking performance after a fluid change.

Troubleshooting

  • Persistent spongy lever/pedal: re-bleed, inspect for soft/expanded hoses, or replace master cylinder seals.
  • Leaking bleeder nipple: replace nipple and copper crush washer if applicable. Re-bleed the circuit after replacement.
  • Brake drag after bleeding: check caliper slider pins, pistons for corrosion, and ensure caliper hardware is correctly torqued.

Regular brake fluid replacement extends the life of seals and maintains stopping power. For parts and OEM-fit brake components specific to the 2009 Yamaha Wolverine 450, MotoSport has a range of pads, hoses, fluids & hardware to keep your machine stopping strong.

Related Shopping Categories

Shop Brake Fluid for a 2009 Yamaha Wolverine 450 ATV.

Shop Brake Bleeders for a 2009 Yamaha Wolverine 450 ATV.

Shop Brake Pads for a 2009 Yamaha Wolverine 450 ATV.

Shop Brake Lines for a 2009 Yamaha Wolverine 450 ATV.

Shop Brake Tools for a 2009 Yamaha Wolverine 450 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.