How to Bleed and Replace Brake Fluid on a 2009 Yamaha Grizzly 450 4X4

Shop parts for a 2009 Yamaha Grizzly 450 4X4 ATV.

This MotoSport guide walks you through safely flushing and bleeding the hydraulic brake system on a 2009 Yamaha Grizzly 450 4X4. Follow these steps exactly to restore firm brake lever/pedal feel, prevent contamination, and protect painted surfaces.

What you’ll need

  • DOT 4 brake fluid (clean, unopened container)
  • Clear tubing to fit bleed nipples
  • Catch bottle for old fluid
  • Ratchet and metric sockets or wrenches matching bleed nipple and caliper mounting bolts
  • Syringe or fluid transfer pump (optional but recommended)
  • Turkey baster or small suction pump to remove old reservoir fluid
  • Clean lint-free rags and isopropyl alcohol for cleanup
  • Rubber gloves and eye protection
  • Torque wrench (for reassembly to Yamaha specs when applicable)

Safety and preparation

  • Work on a level surface with the engine off and key removed.
  • Protect painted surfaces – brake fluid will damage plastics & paint. Cover bodywork with rags or plastic.
  • Use only DOT 4 (Yamaha recommends DOT 4 hydraulic fluid). Never mix DOT 5 (silicone) with DOT 4/3 fluids.
  • Keep the new brake fluid bottle sealed until use to avoid moisture absorption.

Brake system layout & model notes

  • The 2009 Grizzly 450 4X4 uses hydraulic disc brakes front and rear with master cylinders mounted at the handlebar (front) and foot (rear pedal/master cylinder), and separate calipers with bleeder screws. There is no ABS on this model.
  • Reservoirs: front master cylinder reservoir is on the right handlebar; rear reservoir is typically near the frame/engine area for the foot brake. Both use reservoirs with rubber diaphragms and plastic covers held by screws.
  • Caliper bleed screws are accessible from the outside of each caliper; left/right orientation matters when following bleed order.

Overall procedure overview

1) Replace old fluid in reservoirs. 2) Bleed calipers to remove air. 3) Top off reservoirs and verify brake feel. Work one circuit at a time — front and rear separately.

Step-by-step: Replace fluid & bleed the front brakes

  1. Clean the master cylinder reservoir cover area with alcohol. Remove the screws and the cover, then lift out the diaphragm and pad the reservoir edges to prevent contamination.
  2. Use a turkey baster or syringe to remove as much old fluid as possible from the reservoir. Dispose of the fluid safely.
  3. Pour fresh DOT 4 fluid into the reservoir to just below the rim. Keep the cap handy but do not close yet.
  4. Locate the front caliper bleed screws (right and left calipers if dual). Fit clear tubing over the bleed nipple and submerge the other end in a small catch bottle partially filled with fresh fluid to prevent drawing air back in.
  5. Have an assistant slowly squeeze the front brake lever several times and hold it fully applied. With the lever held, open the bleed screw about a quarter-turn until fluid and air bubble pass into the tube, then close the screw before the lever is released. Repeat this pump-open-close cycle until you see only clean fluid with no bubbles. Keep the reservoir topped up during the process to avoid running dry.
  6. If bleeding dual front calipers, bleed the caliper furthest from the master cylinder first, then the closer one. On the Grizzly this typically means bleed the right/left depending on plumbing; if uncertain, bleed the caliper that results in the longest hose route from the master cylinder first.
  7. After bleeding, tighten bleed screws to factory snug level. Clean any spilled fluid. Reinstall the reservoir diaphragm and cover; torque screws snugly but do not over-torque.

Step-by-step: Replace fluid & bleed the rear brake

  1. Locate rear master cylinder reservoir and repeat reservoir fluid removal and refill with fresh DOT 4 as done for the front.
  2. Attach clear tubing to the rear caliper bleed nipple and immerse the other end in the catch bottle.
  3. For the rear brake, the pedal acts as the pump. Have an assistant depress and hold the pedal or use a pedal clamp. Open the bleed screw while the pedal is held, allow fluid/air out, close the screw, then release the pedal. Repeat until fluid runs clear without bubbles. Keep the reservoir topped up during bleeding.
  4. Tighten bleed screw when done and clean any spills. Reinstall reservoir cover.

Single-person bleeding options

  • Use a vacuum pump on the bleed nipple: open the nipple and operate the vacuum pump while adding fresh fluid to the reservoir until no air appears.
  • Use a one-way bleeding kit or syringe method to draw fluid from the caliper bleed screw while pumping the lever/pedal slowly. Follow kit instructions and maintain reservoir level.

Finishing steps & checks

  • Ensure both reservoirs are filled to the specified level and seals are properly seated.
  • Pump the front lever and rear pedal several times to confirm firm, consistent feel. There should be no sponginess.
  • Inspect all fittings, hoses, and calipers for leaks. Road test at low speed in a safe area to confirm braking performance.
  • Properly dispose of old brake fluid per local regulations.

Model-specific notes & common Grizzly 450 issues

  • Older Grizzly 450s can have slightly corroded bleed nipples & caliper fittings if exposed to moisture. Apply penetrating lubricant and use correct metric tools to avoid rounding fasteners.
  • Check rubber hoses for cracking or swelling when replacing fluid — replace hoses showing wear. The hose routing can rub against frame points on some Grizzly models, so inspect clamps and routing.
  • Master cylinder reservoir caps and diaphragms can become brittle. Replace damaged diaphragms or caps to avoid contamination.
  • If brakes remain soft after thorough bleeding, suspect internal master cylinder seals or contaminated calipers; these may require rebuild kits or replacement. MotoSport parts for replacement reservoirs, caliper kits, hoses, and master cylinder components are available.
  • Keep new brake fluid sealed until use; DOT 4 absorbs moisture that degrades performance over time.

Troubleshooting

  • Persistent sponginess: repeat bleeding procedure, ensure no air in reservoir, inspect for leak or soft hoses.
  • Brake drag after bleeding: check caliper pistons and slides for corrosion; ensure bleed screws fully closed and caliper bolts torqued correctly.
  • If one side bleeds only with the other open, verify correct bleed order and that the reservoir never runs low during the process.

Following this MotoSport procedure will restore brake system integrity on your 2009 Yamaha Grizzly 450 4X4. If you run into parts that need replacement or prefer OEM/performance components, find what you need by using the MotoSport parts link above.

Related Shopping Categories

Shop Brake Fluid for a 2009 Yamaha Grizzly 450 4X4 ATV.

Shop Brake Bleeders for a 2009 Yamaha Grizzly 450 4X4 ATV.

Shop Brake Pads for a 2009 Yamaha Grizzly 450 4X4 ATV.

Shop Brake Lines for a 2009 Yamaha Grizzly 450 4X4 ATV.

Shop Brake Tools for a 2009 Yamaha Grizzly 450 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.