How to Bleed & Replace Brake Fluid on a 2020 CFMOTO CFORCE 400S

Shop parts for a 2020 CFMOTO CFORCE 400S ATV.

This MotoSport maintenance guide walks you through safely flushing and replacing the brake fluid on a 2020 CFMOTO CFORCE 400S (MMY). Follow each step carefully. Work on a cool, level surface and use only DOT 4 brake fluid unless CFMOTO specifies otherwise in your owner's manual.

Tools & Supplies

  • DOT 4 brake fluid (fresh, unopened)
  • Brake bleeder wrench or appropriate open-end wrench
  • Clear vinyl tubing (fits bleeder nipple)
  • Catch bottle or jar (partially filled with fluid to submerge tubing end)
  • Turkey baster or fluid syringe (to remove master cylinder fluid)
  • Rubber gloves and safety glasses
  • Clean rags, shop towels
  • Torque wrench (for wheel removal if needed)
  • Zip ties or clamps
  • Service manual or torque spec reference

Safety & Model-Specific Notes

  • Brake fluid is hygroscopic and corrosive. Avoid contact with paint, plastic & rubber; wash any spills immediately.
  • The CFORCE 400S uses a single front master cylinder and a rear master cylinder; confirm which calipers are hydraulic on your specific MMY (some model trims differ in park brake/e-brake routing).
  • Park the ATV with the parking brake off when bleeding to ensure correct fluid flow. Secure the machine on a level stand to keep it stable.
  • Bleeding order recommended: farthest caliper from master cylinder first, then nearest. On CFORCE layouts that commonly means: right rear, left rear (if independent), then front calipers. If unsure, bleed rear then front.
  • If ABS or combined braking system is present on your CFORCE 400S trim, consult service manual; this guide covers conventional hydraulic systems only.

Preparatory Steps

  1. Remove key and disconnect negative battery terminal for safety if you will be working near electrical systems.
  2. Clean master cylinder reservoir cap area to prevent contamination. Remove cap and diaphragm carefully.
  3. Top reservoir to the maximum mark with DOT 4 brake fluid. Keep the cap loosely installed between steps to limit contamination.
  4. Inspect brake lines, hoses, and calipers for leaks, cracking, or damage. Replace damaged components before bleeding.

Basic Brake Fluid Replacement (Two-Person Method)

  1. Have an assistant slowly depress the brake lever or pedal to the floor and hold steady.
  2. Open the bleeder valve on the caliper you are servicing about a quarter turn. Attach clear tubing to the nipple and route the other end into a catch bottle partially filled with fresh fluid (to prevent air being drawn back in).
  3. When the lever is held down, close the bleeder valve. Tell your helper to release the lever slowly. This completes one cycle.
  4. Repeat cycles until clear fluid free of air bubbles flows into the bottle and the master reservoir level remains above the minimum mark. Top reservoir as needednever let it run dry.
  5. Move to the next caliper following the correct sequence (farthest to nearest). Repeat until all calipers show clear, bubble-free fluid.
  6. After final caliper is bled, pump the lever/pedal to build firm pressure. Check for a spongy feel. If spongy, repeat bleeding cycles.
  7. Torque bleeder nipples to service spec (if available) and wipe down. Reinstall master cylinder diaphragm and cap. Clean spilled fluid thoroughly.

One-Person Bleeding (Brake Bleeder Bottle or Vacuum Pump)

  1. Attach a one-way bleeder bottle or vacuum pump to the bleeder nipple via tubing. The one-way device prevents air backflow.
  2. Open bleeder, operate pump or allow bottle mechanism to draw fluid until clear fluid with no bubbles appears. Keep reservoir topped up during the process.
  3. Close bleeder, repeat for remaining calipers, then verify firm pedal/lever pressure.

Power Bleeder Method

  • A power bleeder pressurizes the master cylinder reservoir and pushes fluid through all lines. Use only a compatible unit and set pressure per device instructions (typically low pressure). This method can be faster for complete system flushes.

Final Checks

  • Ensure reservoir is filled to the correct level and cap is secured.
  • Operate brakes at low speed in a safe area to confirm firmness and proper function before returning to normal use.
  • Inspect for leaks around bleeders, calipers, hoses, and master cylinders. Re-torque wheel fasteners if wheels removed.
  • Dispose of old brake fluid per local hazardous-waste regulations.

Maintenance Intervals & Recommendations

MotoSport recommends replacing brake fluid every 1-2 years depending on use, trail conditions, and exposure to moisture. Heavy-duty or wet riding conditions justify annual changes. Keep records of fluid changes for resale value and maintenance tracking.

CFORCE 400S Owner Tips

  • 2020 CFORCE 400S rubber seals and hoses can harden with age; inspect closely on higher-hour machines and replace softened or cracked lines to prevent failure when bleeding.
  • Stock caliper bleeder nipples are smalluse the correct wrench to avoid rounding them off. If damaged, replace the nipple before continuing.
  • If you notice persistent sponginess after thorough bleeding, inspect the master cylinder internals and caliper pistons for corrosion or stickingthese can trap air or prevent proper pressure buildup.
  • Keep an extra small bottle of DOT 4 in your ride kit for emergency top-offs, but avoid long-term storage once opened.

Performing a careful brake fluid flush restores pedal/lever feel and ensures reliable stopping power on your CFORCE 400S. If you encounter unexpected issuesseized caliper pistons, internal master cylinder leaks, or ABS complicationsconsult a qualified technician or an authorized CFMOTO service center.

Related Shopping Categories

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Shop Brake Lines for a 2020 CFMOTO CFORCE 400S ATV.

Shop Brake Tools for a 2020 CFMOTO CFORCE 400S 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.