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Saturday, July 23, 2016

KH500 refurbishment - Brakes

The most recent repair/refurbishment has been on the brakes.

First up was the front brake master cylinder.  This part of the bike, right here...

Every time I would pull the brake lever with the right hand, brake fluid leaked out near the lever.  The lever pushes in a small plunger that pressurizes hydraulic fluid to squeeze the front brake.  The seal for the plunger had given out, and so it had developed a brake fluid leak.  Not clean and not safe!

To perform this task it is necessary to remove the master cylinder assembly from the motorbike, and remove the brake lever from the master cylinder.  After that is where things become difficult.

The plunger must be pushed in while you work, because inside is a spring that keeps tension on the inner parts.  You don't want the spring to send parts flying when you get the retaining ring loose.

The retaining ring is buried down inside a deep and narrow hole.  Decades ago, Kawasaki made and sold a special tool for removing and installing this retaining ring.  It's not possible to purchase one now, so it's necessary to buy a cheap set of retaining ring pliers and grind the body down until they fit inside the hole.

Below:  I mounted a woodworking clamp in the bench vise, and used that clamp to push a wooden dowel to hold the plunger down, while wrestling with getting the retaining ring out.  Game setting:  Nightmare mode.

Eventually (with lots of swearing) I was able to get the retaining ring out, and the inner parts came right out.  The big concern was getting the new parts installed in the correct order, so I placed the old parts just as they came out.

After re-assembly, I bled the brake with fresh fluid and cleaned up the mess.  It now seems to be free of fluid leakage.

The rear brake operates a little differently.  On the rear brake, a foot lever pulls a rod.  This rod is connected to an arm on the rear wheel that rotates a cam.  The cam presses two brake shoes outwards against a brake drum that is set into the rear wheel.

Below:  The rear brake shoes, left and right.  The cam that spreads them is at the top.  There are springs that retract the shoes when the brake is not engaged.  In this picture the springs have been removed.

I removed the brake shoes, cleaned the entire assembly, and then greased the cam and brake shoe pivots (at the bottom of the above image)

Below:  The rear brake drum before cleaing and re-greasing the wheel bearing.

Afterwards I polished the outside of the rear brake carrier and sanded the rear chain sprocket, which lies on the other side of the rear wheel.

At this point all I need to do is to order a pair of tires, have them installed and balanced, and the bike can probably be tried out!

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