How to Change Brake Pads on a 1991 Yamaha YZ250
Shop parts for a 1991 Yamaha YZ250 Dirt Bike.Quick overview of the brake system
The 1991 Yamaha YZ250 uses a hydraulic disc brake system like most modern dirt bikes – a lever or pedal actuates a master cylinder, pressurizing brake fluid through a hydraulic line to the caliper. The caliper squeezes brake pads against a steel rotor to slow the bike. Key parts you'll touch when changing pads are the brake lever or pedal, master cylinder, brake line, caliper, pads, retaining pin/clip, and rotor.
When to replace brake pads – common signs
- Reduced braking power or longer stopping distances
- Squealing, high-pitched noises, or grinding under braking
- Excessive lever or pedal travel before bite
- Visible pad material worn thin – backing plate showing
- Blue or rainbow heat discoloration on the rotor or pad glazing
Inspect pads after muddy rides, long motos, or any event where braking felt off. Because the YZ250 is a 250cc motocross machine, riders frequently push hard on brakes, so check pads more often than on lighter trail bikes.
Tools & supplies you'll need
- Basic wrench or socket set (axle and caliper fasteners)
- Pliers or small punch for retaining pin/clip
- Flat screwdriver or pry tool (to carefully move pads)
- Brake parts cleaner or isopropyl alcohol and a rag
- New brake pads designed for a 1991 Yamaha YZ250
- Small C-clamp or piston spreader (or a clean block of wood)
- Motorcycle stand or secure lift to support the bike
Step-by-step – change the brake pads
- Prepare the bike and workspace. Park on level ground and block the rear wheel. Have good lighting and keep dirt away from the rotor and caliper during the job.
- Support the bike. Use a center stand or motorcycle stand so the front or rear wheel (whichever you're servicing) hangs free. For a YZ250, most riders remove either wheel depending on caliper access.
- Decide whether to remove the wheel. Many YZ250 calipers allow pad replacement with the wheel installed, but removing the wheel can give better access and reduce contamination risk. If you remove the wheel, loosen axle pinch bolts and slide the axle out carefully.
- Locate and remove the retaining clip/pin. The caliper pad retention is usually a pin with a cotter or spring clip. Use pliers or a small punch to remove the clip then slide the pin out. Keep hardware in order for reinstallation.
- Withdraw the old pads. Slide the pads out of the caliper. Note the orientation of shims or wear indicators so you reinstall the new pads the same way.
- Inspect rotor and caliper. Look for deep scoring, warping, or heavy glazing on the rotor. Check the caliper for stuck pistons, corrosion, or debris. Wipe parts with brake cleaner or isopropyl alcohol.
- Compress the caliper piston(s). With the caliper open and no pads in place, use a C-clamp or piston spreader to push the piston(s) back into the caliper bore slowly. Place an old pad or a block of wood against the piston to protect it while compressing. This restores clearance for the new, thicker pads.
- Install new pads. Slide the new pads into the caliper in the correct orientation. Ensure any shims or springs are positioned as they were with the old pads.
- Reinstall retaining pin and clip. Insert the pin through the caliper and pads, then secure the clip or cotter. Make sure it seats fully so pads can't move.
- Reinstall the wheel if removed. Fit the wheel back into the forks or swingarm, align spacers, and torque the axle and pinch bolts to the bike's typical tight setting for a motocross axle. Spin the wheel to verify free rotation.
- Restore hydraulic pressure. With the bike on the ground or stand, pump the brake lever or pedal several times until you feel firm resistance – this brings the pads into proper contact with the rotor and rebuilds hydraulic pressure.
- Test for proper operation. Spin the wheel by hand to confirm the rotor spins freely with minimal drag, then perform a low-speed brake check in a safe area to confirm bite and lever feel before normal riding.
Helpful inspection tips while you're in there
- Measure rotor thickness visually – look for heavy scoring or a ridge at the rotor edge. Replace rotors that are deeply scored or too thin.
- Check for brake fluid leaks at the caliper seals or around the banjo fitting on the brake line.
- Ensure the caliper slides or guide pins move freely; stuck slides cause uneven pad wear.
- Clean dried mud and grit from the caliper bracket and around the rotor; abrasive debris accelerates pad and rotor wear.
- Confirm retaining pin and clip are fully seated and not bent or damaged; replace small hardware if worn.
Bedding in new pads
Proper bed-in helps new pads mate to the rotor. Perform a series of controlled stops from moderate speed to walking speed – about 8 to 10 stops with light to medium pressure, allowing the brakes to cool briefly between efforts. Avoid locking the wheel or using the brakes continuously on a single run. After bedding, recheck hardware tightness and pad fitment.
Notes specific to the 1991 Yamaha YZ250
Most modern dirt bikes including the 1991 Yamaha YZ250 use hydraulic disc brakes with a caliper pressing pads against a rotor. The YZ250 is a competition-focused 250cc motocross bike – frequent, aggressive braking in motos can wear pads faster than trail use. There are no widely known major changes to rotor size or caliper layout that affect basic pad replacement on this model year, so the above garage-level steps will apply to typical YZ250 braking setups. Adjust the order or wheel removal steps based on your exact caliper mount style.
Related Shopping Categories
Shop Brake Pads for a 1991 Yamaha YZ250 Dirt Bike.
Shop Brake Rotors for a 1991 Yamaha YZ250 Dirt Bike.
Shop Brake Lines for a 1991 Yamaha YZ250 Dirt Bike.
Shop Brake Bleeders for a 1991 Yamaha YZ250 Dirt Bike.
Shop Brake Tools for a 1991 Yamaha YZ250 Dirt Bike.
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.
