How to Rebuild a Kawasaki Master Cylinder

by Chris Gilliland

Your Kawasaki motorcycle relies on a properly functioning master cylinder to generate and transmit the hydraulic force that operates its brakes. A leaking or damaged master cylinder will lessen this hydraulic force, reducing the braking capabilities of the motorcycle significantly. While complete replacement of the master cylinder is the easiest method, it is also much more costly. As an alternative, rebuilding the master cylinder with new internal parts can be done relatively easily and inexpensively.

1

Unscrew the front brake master cylinder fluid reservoir and drain the brake fluid using a hand pump. Remove the front master cylinder from the motorcycle. Use a socket wrench to unscrew the master cylinder's mounting bolts and pull the master cylinder away from the handlebar. Use a 14-mm wrench to unscrew the banjo bolt from the end of the master cylinder and pull off the brake line. Allow any remaining brake fluid to drain into a container and wipe immediately with a clean shop towel.

2

Disassemble the master cylinder. Using a pair of pliers, loosen the fluid reservoir's hose clamps and pull the reservoir away from the master cylinder. Remove the reservoir connector on the master cylinder, using a pair of circlip pliers to remove the inner circlip behind the connector's outer seal cover. Pull the connector, seal cover and inner O-ring out of the master cylinder.

3

Locate the rubber dust cover and push rod under the brake lever. Remove the brake lever's lock nut with a 10-mm wrench and unscrew the lever pivot bolt with a flat screwdriver. Pull the brake lever away from the master cylinder. Pull the dust cover and push rod out of the master cylinder. Remove the inner circlip with a pair of circlip pliers and pull the piston out of the master cylinder. Immediately wipe away any remaining brake fluid with a clean shop towel.

4

Clean the master cylinder housing with a brake cleaning spray and a soft brush. Remove any dirt buildup on the inner and outer surfaces of the master cylinder and wipe dry with a clean shop towel.

5

Insert a new piston into the master cylinder and secure it with a new circlip. Insert the original push rod into the master cylinder and cover it a new dust cover. Reattach the brake lever, inserting and tightening the pivot bolt with a flat screwdriver. Screw the lock nut into place and tighten with a 10-mm wrench.

6

Prepare the fluid reservoir connector for installation. Place a new outer seal cover over the connector and replace the inner O-ring. Insert the connector into the master cylinder and secure it in place with a new O-ring.

7

Reattach the fluid reservoir to the master cylinder. Using a pair of pliers to loosen the reservoir's hose clamps, slide the hose onto the master cylinder's connector. Replace the reservoir's rubber diaphragm.

8

Reinstall the master cylinder onto the motorcycle's handlebars, using a socket wrench to insert and tighten the master cylinder's mounting bolts. Reattach the brake line to the master cylinder, using a 14-mm wrench to tighten the banjo bolt.

9

Fill the master cylinder's reservoir with fresh DOT3 brake fluid and bleed the brake circuit until the air trapped within the brake line has been removed.

Warnings

  • close Brake fluid is a solvent and will damage your Kawasaki motorcycle's painted surfaces. Cover any painted surfaces with a towel before beginning the project to protect your Kawasaki motorcycle's finish.
  • close Wear gloves when working with brake fluid to prevent skin irritations or chemical burns.
  • close Have the work performed at a certified Kawasaki service center if you do not feel that you can properly complete this task.

Items you will need

References

About the Author

An avid motorcyclist, Chris Gilliland has immersed himself into the two-wheeled world while balancing work life and raising three daughters. When he is not managing the parts department of a local, multi-line motorcycle dealership, Gilliland can often be found riding, writing or working on his motorcycle blog, Wingman's Garage.

Photo Credits

  • photo_camera detail image by Laima Penekaite from Fotolia.com