The Procedure for Bleeding the Brakes on a Yamaha Bear Tracker

Yamaha's Bear Tracker was a 250 cc all-terrain vehicle intended for light utility work and trail riding. Upon its debut in 1999, the Bear Tracker relied on a drum brake system to slow the ATV; however, the front wheel brake drums were replaced by a hydraulic disc brake system in 2001. While the disc brake provides more braking power over the previous cable-actuated brake drums, the system is prone to water and air infiltration that reduces hydraulic pressure. This mostly is felt as a soft, almost sponge-like feel at the brake lever. Removing trapped air and water from the hydraulic brake is accomplished through a process called "bleeding."

Things You'll Need

• Protective gloves and eye gear
• Socket, 17 mm
• Breaker bar
• Jack
• Thick towels
• Phillips-head screwdriver
• Siphon or hand pump
• Spray-on brake cleaner
• DOT 4 brake fluid
• Shop towels
• Box-end wrench, 14 mm
• Torque wrench
• Box-end wrench, 8 mm
• Clear plastic tubing, 3 feet long
• Plastic container

Instructions

1. Loosen the front wheel lug nuts on both sides of the ATV, using a 17 mm socket and a breaker bar for added leverage. Place a jack under the ATV's engine and raise the front wheels off the ground. Unscrew the lug nuts and pull both wheels off the ATV.

2. Lie a thick towel over the ATV's front fender and fuel tank.

3. Remove the reservoir lid from the front brake master cylinder, located on the right handlebar, using a Phillips-head screwdriver. Pull the inner diaphragm out of the reservoir. Suck the old brake fluid out of the reservoir using a siphon or a hand pump.

4. Clean the reservoir's interior with a spray-on brake cleaner, using the cleaner's applicator straw. Suck the cleaning solvent out of the reservoir with the siphon or hand pump. Fill the reservoir three-quarters full with DOT 4 brake fluid.

5. Wrap a shop towel around the brake hose and union bolt at the end of the master cylinder. Pump the brake lever four to five times, then hold in the lever. Loosen the union bolt a half-turn using a 14 mm box-end wrench. A small amount of brake fluid and air will seep out from the gap between the union bolt and the master cylinder. Tighten the bolt and slowly release the brake lever. Repeat this step two to three times or until air is no longer released with the brake fluid. Tighten the union bolt to 5.1 foot-pounds using a torque wrench. Refill the fluid reservoir until it is three-quarters full.

6. Pull the rubber cap off the bleed screw on the top of the left front caliper located at the end of the left front wheel hub. Slip an 8 mm box-end wrench over the bleed screw, then push a 3-foot length of clear plastic tubing over the bleed screw nozzle. Place the free end of the tubing into a plastic container.

7. Pull in the brake lever and loosen the bleed screw a quarter-turn with the 8 mm box-end wrench. A small amount of brake fluid will travel out of the bleed screw nozzle and into the tubing. Tighten the bleed screw, then slowly release the brake lever. At this point, the fluid trapped in the tubing may appear dirty and contain air bubbles or debris. Repeat this step until the brake fluid does not contain air bubbles and has a clear, light-amber color.

8. Tighten the bleed screw and pull the tubing off the bleed screw nozzle. Wipe up any spilled brake fluid using a shop towel. Push the rubber cap over the bleed screw.

9. Refill the fluid reservoir with DOT 4 brake fluid.

10. Remove the right front caliper bleed screw cap and place the wrench and plastic tubing over the bleed screw nozzle. Bleed the right caliper using the method described above, until the brake fluid is free of bubbles and has a light-amber color.

11. Tighten the bleed screw and pull the tubing off the bleed screw nozzle. Wipe up any spilled brake fluid using a shop towel. Push the rubber cap over the bleed screw.

12. Repeatedly pump the brake lever until you feel resistance. Re-bleed the front brake system if the brake lever still feels soft or spongy.

13. Fill the fluid reservoir until the brake fluid level is above the lower mark imprinted alongside the reservoir's fluid level gauge. Push the inner diaphragm into the reservoir, then reinstall the lid.

14. Mount the front wheels onto the front wheel hubs and loosely screw the lug nuts into place. Lower the wheels to the ground and tighten the lug nuts to 40 foot-pounds using the torque wrench

Tips & Warnings

• Brake fluid is a toxic, caustic chemical. Wear protective gloves and eye wear while servicing your Bear Tracker's brake system to avoid serious skin and eye irritation. Store used brake fluid in a sealed container until it can be taken to recycling center for disposal.

References

• Yamaha YFM250XN Supplement Service Manual; Yamaha Motor Corporation
• Yamaha YFM250XL Service Manual; Yamaha Motor Corporation