How to Bleed and Replace Brake Fluid on a 2012 Yamaha Grizzly 450 4X4
Shop parts for a 2012 Yamaha Grizzly 450 4X4 ATV.
This MotoSport exclusive procedure walks you through safely flushing and replacing the brake fluid on a 2012 Yamaha Grizzly 450 4X4. Follow these steps carefully, use the recommended fluid, and observe safety precautions. If you are not comfortable performing brake service, have a qualified technician do the job.
Notes specific to the 2012 Yamaha Grizzly 450 4X4
- The 2012 Grizzly 450 uses hydraulic disc brakes front and rear with a separate master cylinder for front and rear circuits. Confirm reservoir locations on your unit before starting.
- Yamaha recommends a DOT 4 brake fluid for this model. Always confirm with your owner’s manual and use fresh, unopened fluid from a sealed container.
- Brake hose routing on the Grizzly is exposed to mud and rocks. Inspect hoses, lines, banjo bolts and calipers for damage, leaks, corrosion or indentation before and after bleeding.
- Bleed nipples are on the calipers; some models have angle fittings or covers that must be removed. Keep the banjo bolt crush washers available for inspection and replacement if leaking.
- If your machine has aftermarket handguards, racks, or skid plates, ensure they do not block access to reservoirs or bleed nipples.
Tools & supplies
- DOT 4 brake fluid (fresh, unopened)
- Appropriate wrenches for bleed nipples (usually 8mm or 10mm) and master cylinder reservoir cap
- Clear vinyl bleed hose that fits nipple snugly
- Catch bottle partially filled with old fluid or water to prevent air entry back into bottle
- Vacuum or pressure bleeder (optional for one-person job)
- Clean rags, gloves and safety glasses
- Jack, stands, or ramps to safely lift and secure wheels off the ground if needed
- Brake cleaner and a small container for used fluid
Safety & prep
- Work in a well-ventilated area. Brake fluid is hygroscopic and corrosive to paint – protect painted surfaces.
- Wear gloves and eye protection. Keep brake fluid away from plastic and painted surfaces; immediately wash spills with water.
- Park the Grizzly on a flat surface, set the parking brake (if equipped), and secure the machine so it cannot roll.
- Remove wheel(s) or position machine so you have clear access to bleed nipples and reservoirs.
- Clean reservoir caps and surrounding area to prevent contamination when opening.
Overall strategy
You will replace old fluid in each circuit by topping the reservoir with fresh DOT 4 fluid and opening bleed nipples at the caliper(s) to flush old fluid and air. Perform the procedure for the rear circuit and front circuit separately. Work one circuit at a time so you never drain a reservoir dry.
Step-by-step: Two-person manual bleeder (recommended)
- Remove reservoir cap and diaphragm; clean around the opening and inspect fluid color. Dark fluid indicates replacement is needed.
- Top reservoir to the MAX line with fresh DOT 4 fluid. Do not let the reservoir run dry during bleeding.
- Place clear hose on the caliper bleed nipple and submerge the other end in a catch bottle partially filled so fluid exiting cannot be drawn back in.
- Partner slowly pumps the brake lever or pedal several times and holds pressure. With pressure held, open the bleed nipple a 1/4 to 1/2 turn to allow fluid and air to escape. Close nipple before partner releases lever/pedal. Repeat until fluid flows clear with no bubbles.
- Top reservoir frequently to prevent drawing air into the master cylinder. Repeat pumping/bleeding cycles until no air appears and the lever/pedal feels firm.
- Tighten bleed nipple, wipe the area clean, and reinstall diaphragm and cap. Repeat the process on additional calipers in that circuit if applicable (flush from the caliper farthest from the master cylinder to the nearest).
Step-by-step: One-person vacuum or pressure bleeder
- Attach vacuum pump to the caliper bleed nipple via clear hose and place the other end in a catch container. Or use a pressure bleeder on the reservoir at the recommended low pressure (follow your bleeder tool instructions).
- If using a vacuum pump, open the bleed nipple and operate the pump while topping the reservoir with fresh DOT 4 fluid. Continue until clear, bubble-free fluid flows into the catch bottle.
- If using a pressure bleeder on the reservoir, pressurize the master cylinder and open each bleed nipple in sequence until the fluid runs clear without air. Always top the reservoir as fluid is expelled.
- Close bleed nipples, inspect for leaks, and torque fittings by hand plus a small snug turn; do not over-torque.
Final checks
- Ensure all bleed nipples are tight and the reservoir cap is sealed correctly.
- Clean any spilled fluid from painted areas with plenty of water; brake fluid can damage finish.
- Test brake lever and pedal for firm feel before riding. With the machine on stands, cycle the brakes to confirm proper operation.
- Lower the Grizzly, test brakes at low speed in a safe area to confirm full braking performance.
- Properly dispose of used brake fluid per local regulations.
Maintenance tips & troubleshooting
- If the lever or pedal remains spongy after thorough bleeding, suspect a leak, collapsed hose, or internal master cylinder issue. Reinspect hoses, caliper pistons and banjo fittings.
- Replace soft, swollen, or brittle brake hoses. Hoses exposed to heat, oils, or abrasion can degrade quicker on trail machines like the Grizzly.
- Replace banjo crush washers when reassembling if they show any damage or have been in service a long time.
- Service intervals: inspect fluid annually and replace brake fluid every 1-2 years if you ride in wet/muddy conditions or as specified in your owner’s manual.
- Record the service date and mileage/hours so you know when the next fluid change is due.
Signs you need to service the brakes
- Spongy lever or pedal feel
- Dark or contaminated fluid in the reservoir
- Visible leaks at calipers, lines, or master cylinder
- Poor stopping power or unusual noises when braking
Following this MotoSport guide will keep your 2012 Yamaha Grizzly 450’s braking system responsive and safe. If you find damaged components or persistent air in the system after bleeding, have the brakes inspected and repaired by a qualified technician before riding.
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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.
