How to Bleed and Replace Brake Fluid on a 2007 Yamaha Grizzly 660 4X4

Shop parts for a 2007 Yamaha Grizzly 660 ATV.

This MotoSport guide walks you through a complete, model-specific brake fluid replacement and bleed for the 2007 Yamaha Grizzly 660 4X4. Follow these steps carefully – brakes are safety critical. If you're unsure at any step, contact MotoSport tech support or a qualified mechanic.

What you need

  • Service manual for 2007 Yamaha Grizzly 660 (for torque specs & fluid type confirmation)
  • Brake fluid: use the type specified in your manual. If manual unavailable, use fresh DOT 4 or DOT 3 only as specified by the manufacturer — do not mix different fluid types
  • Clear plastic hose (fits bleeder nipple)
  • Catch bottle for old fluid
  • Wrench for bleeder nipples (usually 8mm or 10mm depending on caliper)
  • Turkey baster or fluid syringe to remove old fluid from reservoirs
  • Clean rags and isopropyl alcohol
  • Latex or nitrile gloves, safety glasses
  • Brake cleaner
  • Optional: vacuum or pressure bleeder, second person for manual pump-bleed

Model notes for the 2007 Grizzly 660

  • The Grizzly 660 uses separate master cylinder reservoirs for front and rear brake systems. Bleed each system independently.
  • No factory ABS system on the 2007 Grizzly 660 — no ABS pump to worry about.
  • Caliper bleeder nipple locations are accessible but can be tight under the A-arms & skid plates. Lifting the front end on tie-downs or removing splash guards may improve access.
  • Some Grizzly 660 models have dual-piston front calipers — inspect pistons/seals while caliper is accessible for leaks or corrosion.
  • Brake hose routing and banjo bolts should be checked for proper torque and no leaks after service.

Preparation

  • Work on a level surface. Secure vehicle on stands so wheels are free to rotate for caliper-bleeding if needed.
  • Clean reservoir caps & surrounding area with brake cleaner so no dirt falls into reservoirs.
  • Wear gloves & eye protection. Brake fluid damages paint & plastics – cover painted surfaces and wipe spills immediately.
  • Confirm correct brake fluid type from the manual and have at least one full unopened bottle on hand.

Step-by-step — Front brake system

  1. Remove reservoir cap and diaphragm. Use a turkey baster to remove as much old fluid as possible from the front master cylinder reservoir. Do not let the reservoir run dry if possible; top with fresh fluid so air does not enter the system beyond what's necessary.
  2. Attach a clear hose to the front caliper bleeder nipple and place the other end into a catch bottle partially filled with fresh fluid to prevent air re-entry.
  3. If using a pressure or vacuum bleeder: follow the tool manufacturer instructions. If manual bleeding, have a helper slowly squeeze the front brake lever several times and hold it to apply pressure.
  4. With lever held, open the bleeder nipple slightly to let fluid and air escape. Close nipple before helper releases lever. Repeat until clear, bubble-free fluid emerges and the lever feel is firm. Replenish reservoir frequently with fresh fluid to avoid drawing air into the master cylinder.
  5. Work from the caliper furthest from the master cylinder first if multiple calipers are present; on the Grizzly 660 the two front calipers bleed independently — treat each caliper separately.
  6. Torque bleeder nipple to spec if provided, or snug securely. Wipe away any spilled fluid and reinstall reservoir cap when done.

Step-by-step — Rear brake system

  1. Locate the rear brake master cylinder reservoir (foot brake). Clean the cap area and remove fluid with a syringe or turkey baster.
  2. Attach clear hose to rear caliper bleeder nipple and route to catch bottle.
  3. Use the same bleed method as front: either pressure/vacuum tool or helper pumping the rear brake pedal. If using a helper, have them press and hold the pedal while you open the bleeder, then close it before pedal release.
  4. Continue until you see clean, bubble-free fluid and a firm pedal feel. Keep reservoir topped up during the process.
  5. When finished, tighten bleeder nipple, wipe clean, and reinstall cap.

Tips for a reliable bleed

  • Always keep the reservoir cap off only as long as necessary — minimize contamination and moisture absorption.
  • Do not reuse old fluid. Brake fluid is hygroscopic — replace it completely during this service.
  • If the lever or pedal remains spongy after bleeding, consider bench-bleeding the master cylinder if removable, or inspect for leaks, worn hoses, or failing caliper seals.
  • Replace any soft or cracked hoses. On the Grizzly 660, inspect hose clamps at the banjo fittings and replace copper crush washers if they show corrosion or deformation.
  • After bleeding, pump brakes several times and test at low speed in a safe area before normal riding.

Torque & hardware checks

  • Torque brake caliper bolts and banjo bolt to values in the service manual. If manual unavailable, tighten banjo bolts to a snug, manufacturer-like feel — replace crush washers when loosening/reinstalling.
  • Inspect and torque master cylinder mounting bolts per manual recommendations.

Disposal & final inspection

  • Dispose of old brake fluid according to local hazardous waste regulations. Do not dump down drains.
  • Inspect all fittings for leaks with the system under pressure. Check for dampness around calipers, lines, and master cylinders after a short test ride.
  • Recheck fluid level after a few short rides — small air pockets can surface and require a follow-up bleed.

Common issues specific to the MMY Grizzly 660 owners

  • Older Grizzly 660s can show caliper piston corrosion from moisture-contaminated fluid; inspect pistons and seals when calipers are accessed. Replace seals or calipers as needed.
  • Banjo bolt corrosion at the master cylinder can cause leaks — replace bolts and crush washers if disturbed.
  • If rear pedal travel is long after bleeding, check the proportioning or linkage for wear & proper adjustment unique to the Grizzly layout.

Follow this MotoSport procedure to restore firm, reliable braking on your 2007 Yamaha Grizzly 660 4X4. Replace any worn components you discover during the job to keep stops predictable and safe.

Related Shopping Categories

Shop Brake Fluid for a 2007 Yamaha Grizzly 660 ATV.

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Shop Brake Lines for a 2007 Yamaha Grizzly 660 ATV.

Shop Brake Tools for a 2007 Yamaha Grizzly 660 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.