How to Bleed and Replace Brake Fluid on a 1999 Yamaha BigBear 350 4x4

Shop parts for a 1999 Yamaha BigBear 350 4x4 ATV.

This proprietary MotoSport guide walks you stepbystep through replacing the brake fluid and bleeding the hydraulic system on a 1999 Yamaha BigBear 350 4x4. Follow these instructions carefully for safe, reliable braking. All work should be performed on a level surface with the engine off, ignition key removed, and the parking brake engaged (if equipped). Wear eye protection and gloves.

What you need

  • Brake fluid use the DOT rating printed on your master cylinder cap (DOT 3 or DOT 4). Do not mix different DOT fluids.
  • Clean catch bottle and clear tubing sized for bleeder nipples
  • Brake cleaner, clean rags, shop towels
  • Small funnel and syringe or turkey baster for reservoir fluid removal
  • Wrench for bleeder nuts (open end; size depends on hardware)
  • Torque wrench for reassembly where needed
  • Jack or stands to lift and secure wheels off the ground
  • Optional: vacuum bleeder or pressure bleeder for faster, cleaner bleeding

Model notes — 1999 Yamaha BigBear 350 4x4

  • The BigBear 350 uses handlebar-mounted master cylinder(s) with a small fluid reservoir; fluid volume is limited so top up frequently during service.
  • Some models route brake lines to both front calipers and a rear caliper; the general bleeding order is farthest wheel from the master cylinder first, finishing with the closest.
  • Inspect hoses for cracks or swelling and banjo bolts for corrosion when the system is drained. Replace any damaged components before bleeding.
  • There is no factory ABS on this model; bleeding is straightforward hydraulic bleeding.
  • Keep brake fluid off painted surfaces & plastics — it will damage finishes. Clean spills immediately with brake cleaner and water.

Preparation

  • Park on level ground and secure the ATV with wheel chocks. Lift and support the ATV so wheels can rotate if bleeding with pedal movement.
  • Locate the master cylinder reservoir on the right handlebar. Clean the area thoroughly to avoid contamination.
  • Remove the reservoir cap and diaphragm. Use a syringe or turkey baster to remove as much old fluid as possible from the reservoir without drawing air into the lines.
  • Top reservoir with new fluid to the recommended level. Keep the cap and diaphragm ready to re-install loosely during the process to minimize contamination.
  • Identify bleeder nipples on each caliper. Fit clear tubing over each nipple and route into a catch bottle partially filled with clean brake fluid to avoid sucking air back in.

Bleeding sequence principle

Always start with the wheel farthest from the master cylinder and work toward the closest. This typical order is:

  • Rear (if hydraulically actuated and farthest)
  • Left front
  • Right front (closest)

Confirm which caliper is farthest on your machine by tracing the brake lines from the master cylinder before starting.

Manual (two-person) bleeding method

  1. Have one person slowly depress the brake lever/pedal about 3/4 travel and hold it.
  2. Open the bleeder nipple a 1/4 to 1/2 turn to let fluid and air escape into the tubing. Close the nipple before the lever/pedal is released. Repeat until clear, bubblefree fluid flows.
  3. Keep the reservoir filled between min & max at all times to prevent drawing air into the system.
  4. Repeat the process for each wheel in the correct sequence.
  5. After the final wheel, pump the lever/pedal with the engine off several times to achieve firm lever feel. Recheck reservoir level and tighten the cap and diaphragm.

One-person vacuum or pressure bleeder method

  • Attach the vacuum/pressure bleeder per manufacturer instructions to the master cylinder or bleeder nipple.
  • Open each bleeder nipple in sequence from farthest to closest until clean fluid without bubbles emerges.
  • Keep reservoir topped and close bleeders before removing equipment. Verify lever/pedal firmness after bleeding.

Replacing the reservoir fluid only (refresh procedure)

  • If lines are recently serviced and no air is present, you can refresh reservoir fluid by repeatedly removing old fluid with a syringe and refilling with fresh fluid until the outflow runs clear. This is not a substitute for a full system bleed if air or contaminated fluid is present.

Inspection & reassembly

  • Tighten bleeder nipples securely; wipe all fittings.
  • Inspect pads, rotors, and caliper slides for wear and proper operation. Replace worn pads and resurface or replace rotors as required.
  • Torque any removed fasteners to factory specs where applicable. Refit and torque wheel nuts to spec when wheels were removed.
  • Properly dispose of used brake fluid per local hazardous waste rules.
  • Test brakes at low speed in a controlled area before returning to normal riding.

Common issues & troubleshooting

  • Spongy lever/pedal after bleeding recheck for air by repeating the bleeding sequence and verify reservoir was never allowed to run low.
  • Leaky bleeder or banjo replace crush washers and tighten to spec; replace damaged fittings or lines.
  • Brake drag after bleeding check caliper pistons and slides for corrosion; clean and lubricate sliding surfaces and verify caliper pistons fully return.

Final safety checks

  • Ensure lever/pedal firmness and full travel are normal. A firm lever with predictable travel is required for safe operation.
  • Verify there are no leaks, and the reservoir cap is secured with the diaphragm in place.
  • Road or trail test cautiously to confirm braking performance before regular use.

For replacement parts, hoses, bleed tools, or brake fluid specific to your 1999 Yamaha BigBear 350 4x4, visit the MotoSport parts page listed above to source correct OEM and aftermarket components.

Related Shopping Categories

Shop Brake Fluid for a 1999 Yamaha BigBear 350 4x4 ATV.

Shop Brake Bleeders for a 1999 Yamaha BigBear 350 4x4 ATV.

Shop Brake Pads for a 1999 Yamaha BigBear 350 4x4 ATV.

Shop Brake Lines for a 1999 Yamaha BigBear 350 4x4 ATV.

Shop Brake Tools for a 1999 Yamaha BigBear 350 4x4 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.