How to Bleed and Replace Brake Fluid on a 2017 Polaris Sportsman 850 SP

Shop parts for a 2017 Polaris SPORTS850SP ATV.

This MotoSport-exclusive guide walks you through safely draining, flushing, and bleeding the hydraulic brakes on a 2017 Polaris Sportsman 850 SP. Follow these steps and safety notes to maintain brake performance and avoid contamination or damage to ABS/EPS components. If you prefer, have a certified technician perform the service.

What you need

  • DOT 4 brake fluid (Polaris specifies DOT 4; do not use DOT 5 silicone)
  • Clear plastic bleed hose and catch bottle
  • Brake bleeder wrench or appropriately sized box wrench
  • Turkey baster or fluid transfer pump (for reservoir removal)
  • Clean rags and isopropyl alcohol for cleanup
  • Jack or ramps and stands to safely support the ATV
  • Latex gloves, safety glasses
  • Service manual for torque specs and diagrams (recommended)

Model-specific notes for the 2017 Sportsman 850 SP

  • The Sportsman 850 SP uses DOT 4 hydraulic fluid throughout the brake system; never mix with DOT 5 silicone fluid.
  • There may be separate reservoirs or a combined reservoir feeding a proportioning valve depending on factory options. Confirm the number of reservoirs on your unit before beginning.
  • ABS or electronic systems are not common on this model, but electric power steering (EPS) can be presentavoid contaminating EPS components with brake fluid.
  • Bleeder screw locations are accessible on each caliper but may be partially hidden by guards; remove plastic guards only if needed and keep dirt out of the system.
  • Always inspect hoses, lines, calipers, and master cylinder boots for cracking or swelling. Replace any soft or damaged hoses prior to bleeding.

Safety and preparation

  • Work on a level surface with the ignition off and key removed. Ensure vehicle is stable on stands or ramps.
  • Protect painted surfaces & plastics from brake fluid, which will damage finishes. Cover nearby bodywork with rags or plastic.
  • Wear gloves and eye protection. Dispose of old fluid per local regulations.

Step-by-step: Drain, replace, and bleed

1. Inspect and prepare

  • Confirm reservoir location(s) and remove caps. Clean around caps thoroughly to prevent dirt entering the system.
  • Siphon out as much old fluid as practical from the reservoir(s) using a turkey baster or fluid transfer pump. Refill with fresh DOT 4 fluid to the fill line to prevent air entry during bleeding.
  • Identify each bleed nipple and label positions if you prefer (front left, front right, rear) so you can follow the bleed sequence consistently.

2. Determine bleed sequence

  • Always start with the caliper furthest from the master cylinder/reservoir and work toward the nearest. If there are separate front/rear reservoirs, use the reservoir associated with the circuit you are bleeding.
  • Typical order: furthest rear caliper – then next-furthest – finish with the caliper closest to the reservoir. If unsure which is furthest, visually trace the brake lines to the master cylinder.

3. Manual (two-person) bleeding method

  • Have a helper slowly press and hold the brake lever or pedal. With the lever/pedal depressed, open the bleed nipple slightly to let fluid and air escape into the clear hose and bottle. Close the nipple before your helper releases the lever/pedal.
  • Repeat pump, hold, open, close cycles until only clean, bubble-free fluid emerges. Keep reservoir topped up during the entire process to avoid introducing air.
  • Move to the next caliper following the sequence until all circuits are clear of air and clean fluid flows.

4. One-person (vacuum or pressure) bleeding

  • Use a hand vacuum pump on the bleed nipple or a pressure-style bench bleeder at the reservoir to draw fluid through each caliper in sequence. Follow tool manufacturer instructions and maintain reservoir fluid level.

5. Final steps

  • When bleeding is complete, top reservoir(s) to the proper level and reinstall caps. Make sure vent caps/seals are clean and seated correctly.
  • Pump the brake lever/pedal several times with the ATV on stands until firm. If the lever/pedal feels spongy, repeat bleeding focusing on the circuit that still feels soft.
  • Check for leaks at bleed nipples, hoses, calipers, and fittings. Torque any fittings to factory spec per your service manual.
  • Clean any spilled fluid from painted/plastic surfaces immediately using water and mild detergent or isopropyl alcohol, then rinse thoroughly.
  • Test ride cautiously in a safe area to confirm firm, consistent braking before normal use.

Troubleshooting & tips

  • Persistent spongy feel after thorough bleeding can indicate internal ABS/proportioning valve air, a failed master cylinder, or contaminated fluid. If repeated bleeding fails, have the master cylinder and valves inspected.
  • Never reuse old fluid or top off with a different DOT rating. Always fully replace contaminated fluid and flush the system if water contamination is suspected.
  • If caliper pistons are sticky or slow to return, remove calipers for rebuild or replacement rather than attempting to force them; rebuilding will prevent uneven brake pad wear.
  • Replace brake pads and rotors as needed. When changing pads, clean and lubricate pad contact points with brake-specific grease where applicable.

Maintenance schedule recommendation

  • Replace brake fluid every 2 years or sooner if exposed to water, heavy use, or harsh environments. Inspect lines and components at every oil change/service interval.

Following this MotoSport proprietary procedure will keep your 2017 Polaris Sportsman 850 SP brakes responsive and reliable. When in doubt, consult a Polaris dealer or a certified mechanic for model-specific torque values and advanced diagnostics.

Related Shopping Categories

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Shop Brake Lines for a 2017 Polaris SPORTS850SP ATV.

Shop Brake Tools for a 2017 Polaris SPORTS850SP 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.