How to Bleed and Replace Brake Fluid on a 2021 Suzuki King Quad 400FSi 4X4 AUTO
Shop parts for a 2021 Suzuki King Quad 400FSi 4X4 AUTO ATV.
This MotoSport-exclusive guide walks you through a safe, reliable brake fluid change and bleed on the 2021 Suzuki King Quad 400FSi 4X4 AUTO. Follow each step carefully. If you’re uncomfortable with any procedure, contact a qualified technician.
What you’ll need
- New DOT 4 brake fluid (Suzuki recommends DOT 4; verify the cap markings)
- Clear plastic bleed hose
- Catch bottle for old fluid
- Open-end wrench set (bleeder nut size commonly 8mm or 10mm — verify on your unit)
- Large syringe or vacuum/pressure brake bleeder (optional but recommended)
- Clean rags, small brush, and brake cleaner
- Latex or nitrile gloves and eye protection
- Jack or ramps and adequate supports to lift wheels if wheel removal is needed
- Torque wrench (for any banjo bolt reassembly)
Important model notes for the 2021 King Quad 400FSi 4X4 AUTO
- Brake system: hydraulic front & rear brakes. Reservoir is located near the handlebar area (right side) for front/rear combined master cylinder on this model &mdash confirm location visually before starting.
- Recommended fluid: DOT 4. Never mix DOT 3 and DOT 5 silicone fluids with DOT 4.
- ABS/Electronics: This model does not use complex ABS systems like larger machines, but check for any brake sensors or electrical connectors before removing components.
- Parking brake: If your unit has a park/brake lever, ensure it’s released before bleeding; if a parking brake cable is present, inspect for corrosion and smooth operation while servicing fluid.
- Hose routing & fittings: Inspect all flexible hoses, banjo bolts, crush washers, and caliper boots for leaks or damage. Replace any compromised components before finishing the job.
Preparation
- Park on level ground, put the unit in park, engage the parking brake, and remove the key.
- Clean around the brake fluid reservoir cap to prevent contamination. Remove cap and diaphragm; cover the opening with clean cloth if you need to walk away briefly.
- Inspect fluid in reservoir for dark color or contaminants. Old fluid will appear brown/black and should be fully replaced.
- Raise the machine safely if you want better access to calipers. Support securely with stands.
Bleeding strategy
Use a full fluid replacement method: remove old fluid from the reservoir, then push fresh fluid through until it runs clear from each bleed nipple. Keep reservoir level above the minimum line throughout to avoid drawing air back in.
Step-by-step bleed & fluid replacement
- Draw out as much old fluid from the reservoir as possible with a syringe or turkey baster. Dispose of it properly.
- Refill the reservoir with fresh DOT 4 fluid to the recommended level. Replace the diaphragm and loosely fit the cap so it’s accessible but sealed from gross contamination.
- Locate bleed nipples at each caliper. Clean around them thoroughly with brake cleaner before loosening to avoid dirt entering the system.
- Attach clear plastic hose to the first bleed nipple and place the other end into a catch bottle partially filled with fresh fluid to avoid drawing air back in.
- Open the bleed nipple about a 1/4 turn. Have an assistant slowly depress the brake lever/pedal and hold it down. Close the nipple. Release the lever. Repeat until fluid coming out is clear and bubble-free. Keep reservoir topped up during the process.
- Bleed in a logical order from farthest caliper to closest to the master cylinder &ndash typically: rear caliper first, then front passenger-side caliper, then front driver-side caliper. Adjust order if your master cylinder location dictates otherwise. The goal is to purge air from the farthest points first.
- For a single-operator method, use a vacuum bleeder or pressure bleeder on the reservoir following the tool manufacturer’s directions; this is often faster and less error-prone than manual pump-and-hold.
- When each caliper runs clear with no air bubbles, tighten the bleed nipple finger-tight and then a final snug with the wrench. Do not overtighten; consult Suzuki torque specs if available for your bleed nipple.
- Top off the reservoir to the correct level, reinstall diaphragm and cap, and ensure the cap is secure.
After bleeding checks
- Firmness test: With the engine off, apply the brake lever/pedal firmly. The lever should feel solid with no sponginess. If spongy, repeat bleeding procedure.
- Inspect for leaks at all fittings, banjo bolts, and bleed nipples while an assistant applies light brake pressure.
- Check brake pad thickness and rotor surfaces for scoring or contamination. Replace pads or rotors as needed before returning to service.
- Road test in a safe area at low speed, performing several moderate stops to confirm pedal feel and braking performance. Re-check fluid level and for leaks after the test ride.
Common pitfalls & MotoSport tips
- Never let the reservoir run dry during bleeding &mdash sucking air back into the system wastes time and can require re-bleeding.
- Do not reuse old DOT fluid. Always replace with fresh DOT 4 and keep the bottle capped & away from moisture.
- Brake fluid is corrosive to paint and plastics. Wipe any spills immediately with brake cleaner and protect painted surfaces before work.
- Replace crush washers on banjo bolts any time you remove hydraulic fittings to ensure a leak-free seal.
- If you find frequent air in the system after correct bleeding, inspect for cracked hoses, collapsed lines, or leaking master cylinder seals &mdash these require part replacement rather than repeated bleeding.
Disposal
Collect used brake fluid in a sealed container. Do not pour it down drains or on the ground. Take it to a local hazardous waste disposal site or authorized recycling center.
When to seek professional service
If bleeding does not produce a firm lever/pedal, if you find evidence of internal master cylinder failure (persistent foam/air despite correct procedure), or if hoses, calipers, or fittings are damaged, stop and have a professional inspect and repair the system.
Following this MotoSport procedure will restore braking performance and extend the safe service life of your 2021 Suzuki King Quad 400FSi 4X4 AUTO. Keep records of service and fluid change dates for future maintenance.
Related Shopping Categories
Shop Brake Fluid for a 2021 Suzuki King Quad 400FSi 4X4 AUTO ATV.
Shop Brake Bleeders for a 2021 Suzuki King Quad 400FSi 4X4 AUTO ATV.
Shop Brake Pads for a 2021 Suzuki King Quad 400FSi 4X4 AUTO ATV.
Shop Brake Lines for a 2021 Suzuki King Quad 400FSi 4X4 AUTO ATV.
Shop Brake Tools for a 2021 Suzuki King Quad 400FSi 4X4 AUTO 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.