How to Bleed and Replace Brake Fluid on a 2013 Polaris Sportsman 90
Shop parts for a 2013 Polaris Sportsman 90 ATV.
This MotoSport proprietary guide walks you through safely replacing and bleeding the hydraulic brake fluid on a 2013 Polaris Sportsman 90 (MMY). Follow steps precisely, use correct tools & fluid, and observe safety precautions. This procedure applies to the factory hydraulic disc/brake system fitted to the Sportsman 90; do not substitute parts or fluids unless compatible with DOT 3/4 specifications noted below.
Tools & materials
- PBS-approved DOT 3 brake fluid (Polaris recommends DOT 3; DOT 4 is acceptable if compatible)
- Clear plastic tubing (inner diameter fits bleed nipple)
- Clean catch bottle or jar
- 10 mm wrench (for bleed nipples on calipers)
- Phillips screwdriver or 2 mm hex for master cylinder reservoir cap screws
- Turkey baster or syringe (to remove old fluid from reservoir)
- Brake cleaner and shop rags
- Gloves & safety glasses
- Bike stand or blocks to elevate ATV safely
- Torque wrench (for caliper hardware if removed)
Model notes for the 2013 Polaris Sportsman 90 (MMY)
- Small-capacity master cylinder reservoir: the Sportsman 90 reservoir holds very little fluid, so top-up frequently while bleeding to avoid drawing air into the system.
- Single-front caliper layout: many 90 models use a single front/rear brake circuit with small bleed nipples; use a small wrench to avoid rounding fasteners.
- Plastic bodywork & paint: spilled brake fluid will damage plastics and paint — cover fenders and clean spills immediately with water and mild detergent.
- Low-height brakes: when pumping the lever/pedal, avoid bottoming out which can draw contaminants; work with small, steady strokes.
Safety first
- Work on a level surface, engine off, key removed.
- Wear gloves & eye protection. Brake fluid is corrosive to paint and plastics.
- Dispose of old fluid per local hazardous-waste regulations.
Preparation
- Park ATV on level ground and block wheels. Elevate front or rear wheel you will bleed so the caliper is higher than the master cylinder reservoir when possible.
- Clean the reservoir cap area to prevent contamination. Remove screws and lift the cap; take out the diaphragm if present and set aside on a clean rag.
- Use a syringe or turkey baster to remove most old fluid from the reservoir, leaving a small amount to prevent sucking air in while topping up.
- Top the reservoir with fresh DOT 3 (or compatible) fluid. Keep the open reservoir covered with a clean rag between steps to limit moisture absorption.
Bleeding sequence
Bleed from the caliper furthest from the master cylinder first, then the nearer caliper — on the Sportsman 90 this typically means rear then front or right then left depending on plumbing. Refer to visual routing; if uncertain, bleed the wheel farthest from the reservoir first.
- Attach clear tubing to the bleed nipple on the caliper. Put the other end in a catch bottle partially filled with clean brake fluid to prevent air being drawn back in.
- With a helper: have helper slowly depress brake pedal or lever 2–3 times and hold it down. While held, open the bleed nipple about a quarter turn with the 10 mm wrench until fluid/air flows into the tubing. Close the nipple, then have helper release the pedal. Repeat until no air bubbles appear and only clean fluid flows.
- If working solo: use a one-man brake bleeder kit or vacuum pump to draw fluid through the nipple while you operate the lever/pedal in short, smooth strokes. Maintain the reservoir level above the minimum at all times.
- After each caliper cycle, top the reservoir to the recommended level. Replace the diaphragm and cap hand-tight when finished with that circuit.
- Repeat for the next caliper(s) until all circuits show steady, bubble-free fluid and firm pedal/lever feel.
Master cylinder flush & reservoir replacement
- If you removed most fluid initially, refill reservoir with fresh DOT 3 fluid and bleed until clean fluid runs through and no bubbles are visible.
- Do not mix DOT 3 and DOT 5 silicone fluid. If DOT 4 was previously used, DOT 4 may remain; verify previous service records if possible.
Final checks & torque
- Tighten bleed nipples to factory snug torque (small wrench tight — avoid overtightening). If you removed calipers or lines, torque bolts per service manual specs.
- Clean all spilled fluid with water & mild detergent immediately. Reinstall reservoir cap and diaphragm securely.
- Check pedal/lever for firm engagement. If spongy feel remains, repeat bleeding cycle until solid.
- Test brakes at slow speed in a safe area before normal riding.
Maintenance tips specific to the Sportsman 90
- Bleed every 12 months or sooner if you notice softness, contamination, or after any brake-line work.
- Inspect brake lines for chafing against frame and plastic panels common on small ATVs; replace cracked or bulging hoses immediately.
- Keep fastener sizes and small parts organized. The Sportsman 90 uses smaller hardware that can be easily lost.
- If the brake lever/pedal bottoms out despite bleeding, inspect master cylinder seals and caliper pistons for wear & leakage; seal kits are often inexpensive and extend system life.
Following this MotoSport proprietary procedure ensures reliable brake performance on your 2013 Polaris Sportsman 90. If you need model-specific components, use our parts link above to find brake fluid, seals, bleed kits, and replacement hardware.
Related Shopping Categories
Shop Brake Fluid for a 2013 Polaris Sportsman 90 ATV.
Shop Brake Bleeders for a 2013 Polaris Sportsman 90 ATV.
Shop Brake Pads for a 2013 Polaris Sportsman 90 ATV.
Shop Brake Lines for a 2013 Polaris Sportsman 90 ATV.
Shop Brake Tools for a 2013 Polaris Sportsman 90 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.