How to Bleed & Replace Brake Fluid on a 1990 Yamaha Blaster

Shop parts for a 1990 Yamaha Blaster ATV.

This proprietary MotoSport guide walks you through a safe, complete brake fluid change and bleed on a 1990 Yamaha Blaster. Follow every step, use the right tools and fluids, and inspect brake hardware as you go. Braking performance is critical on a small, light two-stroke ATV like the Blaster, so take your time and use fresh parts where needed.

What you'll need

  • Correct brake fluid (see reservoir cap for DOT spec; most Blaster systems accept DOT 3 or DOT 4)
  • Clear plastic tubing that fits over bleeder nipples
  • Catch bottle (marked for used brake fluid)
  • 10mm or appropriate wrench for bleeder nipples
  • Phillips & flat screwdrivers
  • Clean rags and safety glasses
  • Disposable gloves
  • Vacuum or pressure bleed kit (optional but speeds job)
  • New crush washers or banjo bolt washers, if applicable
  • Torque wrench (recommended for reassembly)
  • Brake cleaner and a small brush

Safety & prep

  • Work on a level surface with the engine off, key removed.
  • Protect painted surfaces from brake fluid; it will damage paint and plastics. Cover areas with rags.
  • Park the Blaster securely on a stand so wheels are free to turn if needed.
  • Confirm the brake reservoir cap lists the DOT rating. Use only the specified fluid.

Overview of the Blaster braking layout

The 1990 Yamaha Blaster uses compact hydraulic brake components and small reservoirs. The front/rear layout is simple but the hardware can be old and brittle on a 30+ year machine. Expect small bleeder nipples and plastic fittings that may crack; handle them gently and replace any suspect parts.

Step 1 – Remove old fluid from reservoir

  • Open the brake fluid reservoir cap. Wipe the surrounding area clean to prevent contamination.
  • Using a turkey baster or syringe, remove as much old fluid as possible from the reservoir. Dispose of used fluid safely.
  • Refill reservoir with fresh brake fluid up to the maximum mark. Keep the cap off but protected from dirt while you bleed.

Step 2 – Identify bleed order

Bleed starting at the brake caliper or wheel that is furthest from the master cylinder and finish with the closest. On many small ATVs that means rear then front, but verify the master cylinder location on your Blaster and use the furthest-first rule.

Step 3 – Manual two-person bleed (recommended if no vacuum/pressure kit)

  • Fit clear tubing over the bleeder nipple and put the other end in your catch bottle partially filled with fresh fluid to prevent air from being drawn back in.
  • Have an assistant slowly depress the brake lever/pedal several times and hold it down.
  • With the lever held, open the bleeder nipple one-quarter to one-half turn. Fluid and air will flow into the tubing. Close the nipple before the assistant releases the lever.
  • Repeat: pump, hold, open nipple, close nipple. Keep reservoir topped up to prevent air re-entry.
  • Continue until you see only clear fluid with no bubbles coming out and the lever/pedal feels firm.
  • Torque bleeder nipple to specification if known or snug it securely; use new crush washers if the fitting uses them.

Step 4 – Single-person vacuum/pressure bleed

  • If using a vacuum pump at the caliper: attach tubing from pump to bleeder, open nipple, and draw fluid while keeping the reservoir topped. Close nipple when finished.
  • If using a pressure reservoir kit: pressurize the master cylinder with the kit, then open each bleeder in sequence until fluid runs clear of bubbles.
  • Always monitor reservoir level during either method to avoid introducing air.

Step 5 – Replace all fluid and final checks

  • After bleeding each circuit until clear, fill the reservoir to the MAX line and reinstall the cap with a clean gasket.
  • Work the lever/pedal several times to confirm a firm feel. Recheck bleeder nipples for leaks.
  • Wipe any spilled fluid from components and apply brake cleaner to remove residue from non-painted surfaces. Rinse paint damage mitigation: if fluid contacted paint, wash immediately with water & mild detergent.
  • Test brakes at low speed in a safe area before returning to regular use.

Maintenance intervals & recommendations

  • Replace brake fluid every 1-2 years or whenever you detect sponginess, contamination, or moisture ingress.
  • Inspect hoses, banjo bolts and bleeder nipples for corrosion or leaks. Rubber lines on older Blasters may be brittle & should be replaced if cracked.
  • Replace crush washers whenever a banjo bolt or bleeder is loosened to ensure a proper seal.
  • Store brake fluid sealed and away from moisture; brake fluid is hygroscopic and absorbs water over time.

Blaster-specific owner notes

  • 1990 Yamaha Blaster is a lightweight two-stroke ATV with compact hydraulic components – bleeder nipples and reservoirs are small, so take care not to strip or crack them.
  • Original hardware may be corroded or previous owners may have used incorrect fluids; always verify the DOT rating stamped on the reservoir cap before adding fluid.
  • Plastic reservoir caps and tabs can become brittle with age; handle gently and have a replacement on hand if the cap or seal fails.
  • Brake pedal & lever pivots are simple but can seize from dirt and corrosion. Clean and lubricate pivots after fluid work, avoiding any lubricant near pads or rotors.
  • Because the Blaster is a two-stroke, expect more frequent cleaning and inspection of brake areas after riding in wet/muddy conditions; debris can work into caliper pistons and bleed screws.
  • Carry spare crush washers and a small bleeder wrench on long rides if you rely on an older machine for trail use.

Troubleshooting

  • If brake lever remains soft after thorough bleeding, check for air in lines, a leaking master cylinder, degraded hoses, or contaminated master cylinder seals. Replace faulty components rather than repeatedly bleeding.
  • If fluid looks dark or has particles, flush until clear and inspect caliper(s) for corrosion or deteriorated seals.
  • If a bleeder nipple is rounded or seized, replace the caliper or nipple; do not risk rounding out the fastener and causing a costly repair.

Regular fluid changes and careful inspection will keep a 1990 Yamaha Blaster stopping reliably. If you need replacement hardware, parts, or tools for the job, visit the parts link above and choose components specific to your MMY.

Related Shopping Categories

Shop Brake Fluid for a 1990 Yamaha Blaster ATV.

Shop Brake Bleeders for a 1990 Yamaha Blaster ATV.

Shop Brake Pads for a 1990 Yamaha Blaster ATV.

Shop Brake Lines for a 1990 Yamaha Blaster ATV.

Shop Brake Tools for a 1990 Yamaha Blaster 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.