How to Bleed & Replace Brake Fluid on a 2017 Polaris Sportsman BIG BOSS 6x6 570 EPS

Shop parts for a 2017 Polaris Sportsman BIG BOSS 6x6 570 EPS ATV.

This MotoSport-exclusive service guide walks you through a complete brake fluid replacement and bleed on the 2017 Polaris Sportsman BIG BOSS 6x6 570 EPS. Follow these steps precisely – brakes are critical to safety. If you’re unsure at any step, contact a qualified technician.

What you’ll need

  • DOT 4 brake fluid (new, unopened bottle). MotoSport recommends using a high-quality DOT 4 that meets FMVSS 116.
  • Clear vinyl tubing that fits snugly over each bleed nipple
  • Brake fluid catch bottle or container (transparent so you can watch for air)
  • Box wrench set sized to bleed nipples (usually 8mm or 10mm)
  • Turkey baster or fluid suction pump (to remove old fluid from reservoir)
  • Clean rags, brake cleaner, and gloves
  • Floor jack or ATV stand and wheel chocks
  • Optional: vacuum or pressure brake bleeder for faster, cleaner bleeding
  • Torque wrench for wheel lug nuts if wheels are removed

Safety & model-specific notes

  • 2017 Sportsman BIG BOSS 6x6 570 EPS uses hydraulic brakes and is factory-configured with multiple calipers due to the 6x6 drivetrain. Locate the master cylinder reservoir on the handlebar area; it feeds all calipers via a split line system.
  • The EPS system is electrical power steering. Turning the key on briefly to cycle systems is fine for bleeding, but never run the engine during bleeding. Avoid prolonged key-on cycles without the engine running to prevent battery drain.
  • Brake fluid will damage paint and plastics. Protect bodywork and clean spills immediately with brake cleaner.
  • Dispose of used fluid in accordance with local regulations & never reuse old fluid.
  • MotoSport recommends replacing fluid every 1-2 years or sooner if the fluid is dark or contaminated.

Preparation

  • Park on a level surface, engage parking brake, and chock wheels. Remove the key.
  • If you plan to access calipers more easily, raise the ATV on stands and remove wheels. For a 6x6, removal of outer wheels may be necessary to reach rear calipers.
  • Clean around the master cylinder cap, then remove the cap and diaphragm. Use a turkey baster to remove as much old fluid as possible from the reservoir to reduce contamination when refilling.
  • Top reservoir with fresh DOT 4 fluid to the fill line. Keep the cap off during bleeding but protected from dirt.

Bleeding strategy & sequence

MotoSport recommends bleeding starting from the caliper farthest from the master cylinder and working toward the nearest. On the BIG BOSS 6x6 570 EPS this typically means: rear-most caliper(s) first, then intermediate/rear-split calipers, ending with the front caliper(s). Identify which caliper is farthest by tracing the brake lines from the master cylinder.

Manual bleeding procedure (step-by-step)

  1. Attach a clear vinyl tube over the bleed nipple and place the other end into a catch bottle partially filled with fresh fluid to prevent air being drawn back in.
  2. Have a helper sit on the ATV seat (or apply steady pressure to the brake lever/pedal) to press the brake and hold it depressed. If using the hand brake lever, use the lever hold method; for foot brake, maintain steady pressure on the pedal.
  3. Open the bleed nipple about a quarter-turn with the wrench. Fluid and air will flow into the tube. Close the nipple before your helper releases the lever/pedal.
  4. Repeat: pump or press the brake, open nipple, close nipple, release brake. Keep reservoir topped with fresh fluid between cycles to avoid introducing air into the master cylinder.
  5. Continue cycles until clear, bubble-free fluid flows and the brake lever/pedal feels firm. Move to the next caliper in the sequence and repeat.
  6. If you have multiple bleed ports on a caliper or a dual circuit, make sure each line is bled following the same far-to-near rule.

Using a vacuum or pressure bleeder

  • Attach the vacuum pump to the bleed nipple or set up the pressure bleeder on the master cylinder reservoir following the bleeder manufacturer’s instructions.
  • Open each bleed nipple in sequence while drawing fluid until clear, air-free fluid runs. Keep reservoir filled. Close each nipple before moving on.
  • Pressure systems speed the job and reduce helper fatigue but verify caps and seals to avoid overpressure.

Finishing steps

  • When all calipers are bled and no air is visible, top the master reservoir to the proper level, reinstall the diaphragm and cap securely.
  • Clean bleed nipples, remove tubing, and reinstall wheels if removed. Torque wheel lug nuts to the manufacturer specification.
  • Test brake lever/pedal feel. It should be firm with minimal free play. If soft or spongy, repeat bleeding focusing on suspected circuit with persistent air.
  • Conduct a cautious low-speed road test in a safe area to confirm braking performance before normal operation.

Troubleshooting

  • Persistent soft pedal after repeated bleeding could indicate a leak, collapsed hose, or master cylinder problem — inspect lines, fittings, and calipers for leaks or damage.
  • If fluid turns dark quickly, brake system may be contaminated or internal component failure exists. Replace fluid and inspect components.
  • If a caliper will not build pressure, consider caliper rebuild or replacement.

Perform routine inspections of brake lines, hoses, fittings, and calipers on your Polaris SPORTSBB570EPS model. MotoSport advises replacing any rubber hoses older than 5 years or hoses showing cracking or swelling. Properly bled, fresh DOT 4 fluid will keep your BIG BOSS stopping reliably for trail & work use.

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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.