How to Bleed and Replace Brake Fluid on a 2021 Polaris Sportsman 570

Shop parts for a 2021 Polaris Sportsman 570 ATV.

This MotoSport exclusive guide walks you through a safe, thorough brake fluid replacement and bleed on a 2021 Polaris Sportsman 570. Follow every step exactly, use proper PPE, and dispose of used fluid responsibly. This procedure is written for the stock hydraulic disc brake system on the Sportsman 570. If your machine has aftermarket brakes or an ABS/Traction control option, adapt procedures accordingly and proceed with caution.

What you need

  • DOT 4 brake fluid (Polaris-approved equivalent recommended)
  • Clear hose and catch bottle with clamp
  • Brake bleeder vacuum pump or hand pump (optional but recommended)
  • Torque wrench for caliper and bleed screw hardware
  • 10 mm or appropriate wrench for bleed nipples
  • Clean rags, brake cleaner, gloves and eye protection
  • Zip ties or bungie to keep brake lever depressed if needed
  • Disposable funnel, turkey baster or syringe to remove old fluid from reservoir

Model notes – 2021 Polaris Sportsman 570

  • The Sportsman 570 uses hydraulic disc brakes front and rear with a master cylinder reservoir(s) accessible from the handlebar area and/or under the hood depending on trim. Some trims share a single reservoir for both circuits; others use distinct circuits. Confirm reservoir layout before starting.
  • If your machine is equipped with Electronic Power Steering (EPS) or a factory accessory that ties into the front end, be careful not to apply pressure to EPS components during brake work.
  • Brake caliper bleed nipple location is exposed on each caliper; keep fittings clean to avoid contamination. Replace corroded nipples before bleeding.
  • Polaris recommends DOT 4 fluid for best performance; do not mix DOT 5 silicone fluid with DOT 3/4/5.1 systems.

Safety first

  • Work on a level surface with the engine off and key removed.
  • Do not allow brake fluid to contact painted surfaces – it damages paint. Keep water out of the system at all times.
  • Wear gloves and eye protection. Keep rags handy to wipe spills immediately.
  • Never reuse brake fluid; collect and dispose of it according to local regulations.

Overview of the procedure

1) Prepare and inspect. 2) Remove old fluid from reservoir. 3) Refill with fresh DOT 4. 4) Bleed each circuit, farthest caliper from reservoir first. 5) Confirm lever/pedal firmness and top off reservoir. 6) Road test at low speed and recheck.

Step-by-step: bleed and replace brake fluid

1. Prep the ATV

  • Place the ATV on a firm stand so both wheels are free where possible. Stabilize the machine; use wheel chocks.
  • Clean around the master cylinder reservoir cap to prevent contamination. Remove cap and diaphragm carefully.
  • Note reservoir level and color of fluid; very dark fluid indicates overdue service.

2. Remove old fluid from reservoir

  • Use a turkey baster, syringe or vacuum pump to extract as much old fluid from the reservoir as possible without letting air into the master cylinder bore.
  • Wipe the reservoir clean with lint-free rag. Reinstall the diaphragm and cap loosely while working to minimize contamination.

3. Refill with new fluid

  • Fill the reservoir with fresh DOT 4 to the specified level. Keep the cap off but place diaphragm loosely to reduce contamination and to vent during bleeding.

4. Identify bleed order

  • Determine which caliper is farthest from the master cylinder reservoir. Typical order: farthest caliper first, then next farthest, finishing with the caliper closest to the reservoir.
  • If the Sportsman uses separate front and rear circuits with dedicated reservoirs or internal routing, bleed each circuit independently following farthest-to-closest rule per circuit.

5. Bleeding procedure – vacuum or manual

Vacuum bleeder method (recommended for clean, repeatable results):

  • Attach clear hose to caliper bleed nipple and place other end into catch bottle partially filled with old fluid to prevent air from being drawn back in.
  • Use vacuum pump on the bleed nipple and open the nipple one quarter turn. Pull vacuum while an assistant slowly squeezes the brake lever or depresses the pedal several times, then holds pressure.
  • Watch for clear, bubble-free fluid in the hose. Close the bleed nipple before the assistant releases the lever or pedal to avoid sucking air back into the system.
  • Repeat until fluid runs clear and free of air bubbles, then torque bleed nipple to spec (light torque; overtightening can round threads). Wipe clean.

Manual pump method (if no vacuum tool):

  • Attach hose to bleed nipple into catch bottle. Have an assistant slowly pump the lever/pedal several times and then hold pressure. Open the bleed screw to allow fluid/air out, then close before the assistant releases pressure. Repeat until clear fluid appears.
  • Be disciplined: never let the reservoir run low during bleeding or you will introduce air into the system and restart the process.

6. Bleed sequence examples

  • If the master reservoir feeds both front calipers and the rear: bleed the rear caliper first (usually farthest), then the front calipers, finishing with the caliper closest to the reservoir.
  • If front and rear have separate circuits, bleed the entire front circuit farthest-to-closest, then the rear circuit farthest-to-closest.

7. Final topping off & checks

  • Top the reservoir to the correct level with DOT 4. Reinstall diaphragm and cap securely.
  • Operate the brake lever/pedal multiple times to confirm a firm, consistent feel. If sponginess remains, continue bleeding.
  • Inspect bleed nipples and hoses for leaks. Clean any spilled fluid and check rotor surfaces for contamination – clean with brake cleaner if needed.

8. Torque & hardware inspection

  • Ensure caliper mounting bolts and bleed nipple fittings are torqued to manufacturer spec. Replace any rubber hoses that are cracked or showing wear.
  • Replace master cylinder reservoir cap O-ring or diaphragm if damaged to preserve system sealing.

Troubleshooting

  • Persistent soft lever after thorough bleeding: suspect internal master cylinder leak, collapsed hose, or air trapped in ABS/valve body if equipped.
  • Brake drag after bleeding: check caliper pistons for proper return, hose condition, and that bleed nipple is closed fully.
  • If you find foamy fluid in the reservoir, continue bleeding until fluid clears; foaming indicates air contamination.

Aftercare and testing

  • Carry out a low-speed functional test in a safe area to confirm braking performance. Re-inspect for leaks after the first ride.
  • Record the service date and fluid type on your maintenance log. Plan to replace brake fluid every 1-2 years or per riding conditions.

MotoSport tips – keep your Sportsman 570 safe and consistent

  • Always buy fresh DOT 4 fluid from a sealed container; don't reuse partially used bottles kept for long periods.
  • If you ride in wet, salty, or high-humidity environments, bleed more frequently. Moisture in brake fluid reduces boiling point and braking performance.
  • Keep a small bleed kit and extra fluid in your garage for intermediate maintenance; quick attention prevents larger failures.

Perform this service carefully or have a qualified technician complete it if you are uncomfortable. Properly bled brakes are vital for safe operation of your Polaris Sportsman 570.

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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.