1989 Yamaha YSR50 Brake Bleeding Guide
Shop parts for a 1989 Yamaha YSR50 Motorcycle.The 1989 Yamaha YSR50 uses a hydraulic disc brake at the front and a mechanical drum brake at the rear. The front disc gets its fluid from a small master cylinder and reservoir on the right handlebar, and that is the only circuit that needs bleeding. The rear drum is adjusted rather than bled. Fresh fluid in the front system keeps this little sportbike stopping confidently.
When and Why to Bleed
Brake fluid absorbs moisture from the air. As the water content rises, the boiling point drops, and hard braking can heat the fluid enough to form vapor. Vapor compresses, so the lever goes soft. Moisture also corrodes internal parts, a common cause of stuck calipers and leaking master cylinders on older bikes.
- Spongy lever feel
- Dark or contaminated fluid
- Long storage periods
- After replacing the hose, caliper parts, or master cylinder parts
Tools and Supplies
- Fresh brake fluid of the type marked on the master cylinder reservoir cap, from a sealed container
- A box-end wrench that fits the bleeder valve
- Clear tubing that fits snugly over the bleeder
- A catch bottle
- A small syringe
- A screwdriver for the reservoir cap
- Penetrating oil and rags
Prep Work
Support the bike securely so it stays upright. Turn the handlebars to level the reservoir. Cover the bodywork and tank with rags, because brake fluid can damage paint and plastic. Rinse any spill with water right away. Clean the reservoir cap before opening it, and soak a rusty bleeder with penetrating oil before loosening.
Bleeding Instructions
- Remove the reservoir cap and diaphragm.
- Draw out most of the old fluid, keeping the reservoir from running empty.
- Wipe out residue and refill with fresh fluid.
- Attach the clear tube to the caliper bleeder with the free end in the catch bottle.
- Squeeze and hold the lever.
- Open the bleeder about a quarter turn.
- Close the bleeder before releasing the lever.
- Repeat, topping off the reservoir every couple of strokes.
- When clean, bubble-free fluid comes through, close the bleeder snugly.
Rear Brake Notes
The rear drum has no hydraulic components, so there is nothing to bleed at the back. Check the pedal free play and adjustment, look at the wear indicator, and make sure the brake releases fully.
Good Habits
- Use smooth, full lever strokes.
- Inspect the brake hose for cracks or bulges.
- Keep fluid off the disc and pads.
- Throw away collected fluid rather than reusing it.
Testing Your Work
Fill the reservoir to the correct level, reinstall the diaphragm and cap, and clean up spills. Check the bleeder and fittings for leaks, and dispose of the old fluid properly. The lever should feel firm and steady without sinking. Spin the front wheel to confirm there’s no drag, then test both brakes at low speed in a safe area before riding.
When to See a Shop
If the lever stays soft, firms only after pumping, or you find leaks at the caliper or master cylinder, the seals are likely worn. A rebuild or replacement may be needed, and a shop can help.
Related Shopping Categories
Shop Brake Fluid for a 1989 Yamaha YSR50 Motorcycle.
Shop Brake Lines for a 1989 Yamaha YSR50 Motorcycle.
Shop Brake Pads for a 1989 Yamaha YSR50 Motorcycle.
Shop Stands for a 1989 Yamaha YSR50 Motorcycle.
Shop Brake Tools for a 1989 Yamaha YSR50 Motorcycle.
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.
