How to Bleed and Replace Brake Fluid on a 1987 Yamaha YFM200 Moto-4
Shop parts for a 1987 Yamaha YFM200 ATV.
This MotoSport guide gives step-by-step, owner-friendly instructions to fully replace and properly bleed the hydraulic brake system on a 1987 Yamaha YFM200 Moto-4. Follow all safety precautions, use quality parts and brake fluid, and inspect components while you work. If you are unsure at any point, stop and consult a qualified technician.
Safety & preparation
- Work on a cool, level surface and secure the ATV on jack stands or a lift so wheels can turn freely.
- Wear eye protection and nitrile gloves. Brake fluid is corrosive to paint and plastic; protect surfaces and clean spills immediately.
- Use only DOT-rated brake fluid recommended for your vehicle. If the factory manual is unavailable, DOT 3 or DOT 4-compatible fluid is commonly used on older Yamaha ATVs — do not mix mineral oil-style fluids (e.g., bicycle) with DOT fluids.
- Gather tools: clear plastic tubing to fit over bleed nipples, a catch bottle, a small siphon or syringe, a turkey-baster or fluid transfer pump, a bleeder wrench or correctly sized open wrench, clean rags, and (optional) a vacuum or pressure bleeder.
Model notes for the 1987 YFM200 Moto-4
- Age-related issues to watch for: hardened or cracked rubber hoses, caliper piston corrosion, and reservoir cap gasket deterioration. Replace hoses and seals if they show damage or leakage.
- The brake master cylinder reservoir is small – plan to top off fluid frequently during the procedure to avoid introducing air.
- Bleed nipples can be tight or corroded on older calipers. Apply penetrating lubricant and use the correct wrench to avoid rounding the nipple.
- Moto-4 brake lines on older ATVs may be a single hydraulic circuit or separate circuits for front and rear. Confirm which calipers are hydraulic on your unit before starting so you can follow the correct bleeding sequence.
Overview of the process
Replace the fluid in the reservoir, then bleed each caliper to remove air. If you have a single hydraulic circuit, bleed each caliper in the recommended order (farthest from the master cylinder first). If the system is tandem, follow front/rear order per your layout. The key is keeping the master reservoir from running dry throughout.
Step-by-step replacement and bleeding
- Inspect components: Check lines, fittings, calipers, and reservoir cap – replace cracked hoses, brittle tubing, or a damaged cap gasket before adding fluid.
- Clean reservoir area: Remove dirt around the cap. Open the cap slowly to relieve any pressure. Remove the diaphragm and reservoir cap and clean visibly dirty fluid from the top.
- Siphon old fluid: Use a turkey-baster or fluid transfer pump to remove as much old fluid from the reservoir as possible. Dispose of fluid responsibly.
- Top up with fresh fluid: Add new DOT-rated brake fluid to the reservoir to the maximum level. Keep the reservoir cap off but loosely positioned so you can watch the level while bleeding.
- Locate bleed nipples: Fit clear tubing over the caliper bleed nipple and route it into a catch bottle partially filled with clean brake fluid to prevent air reintroduction.
- Bleeding order: Start with the caliper farthest from the master cylinder and work toward the nearest. If unsure which is farthest, start with the rear and then front calipers. For dual-circuit setups follow the circuit order for that system.
- Manual bleed method: Have an assistant slowly apply and hold the brake lever (or pedal) to build pressure. Loosen the bleed nipple about a quarter turn until fluid and air bubbles flow into the tubing. Tighten the nipple, then have the assistant release the lever. Repeat pump/open/close cycles until clear, bubble-free fluid flows and no air is seen. Keep reservoir topped between cycles.
- One-person vacuum or pressure method: Connect a vacuum pump to the bleed nipple or a pressure bleeder to the reservoir per the tool instructions. Draw fluid until clear and bubble-free fluid appears, topping the reservoir as needed. These methods reduce mess and are ideal for older calipers that trap air.
- Final top-off and cap: Once each caliper yields clear fluid and no air, fill the reservoir to the proper level and reinstall the diaphragm and cap securely. Wipe every surface clean of spilled brake fluid.
- Test and inspect: With the ATV still secured, operate the brake lever/pedal repeatedly to confirm firm hydraulic feel. Check for leaks at bleed nipples, line fittings, and calipers. Lower the ATV, then perform a low-speed controlled test in a safe area to confirm braking performance.
Troubleshooting & tips
- If the lever or pedal remains spongy after thorough bleeding, re-check for hidden air entry points, leaking seals, or a failing master cylinder. Re-bleed the entire system if a leak was found and repaired.
- Stubborn air pockets: angle the ATV or rotate wheels while bleeding to help dislodge trapped air in caliper bores.
- Corroded bleeder screws: if a screw rounds or breaks, replace the caliper hardware or caliper assembly as needed to avoid compromised braking safety.
- Replace rubber hoses on older units proactively; age-embrittled hoses can expand under pressure and reduce brake feel.
Parts & replacement items to consider
- Brake fluid (DOT 3 or DOT 4 as appropriate)
- Bleeder screws and new copper crush washers or seals if used
- Replacement rubber brake hoses and clamps for aged lines
- Caliper rebuild kits if pistons or seals show corrosion or leakage
- Reservoir cap diaphragm and cap seal
Maintenance schedule recommendation
For a 1987 YFM200 Moto-4 used recreationally, replace brake fluid every 1-2 years or sooner if exposed to moisture or heavy use. Inspect lines and rubber components annually and replace aged parts proactively to maintain braking reliability.
Perform the job methodically and keep everything clean. Proper bleeding and fresh fluid restore braking performance and extend the life of hydraulic components on these classic Moto-4 ATVs.
Related Shopping Categories
Shop Brake Fluid for a 1987 Yamaha YFM200 ATV.
Shop Brake Bleeders for a 1987 Yamaha YFM200 ATV.
Shop Brake Pads for a 1987 Yamaha YFM200 ATV.
Shop Brake Lines for a 1987 Yamaha YFM200 ATV.
Shop Brake Tools for a 1987 Yamaha YFM200 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.