front brake problem on 1982 XJ550

Engine is still running great!

My front breaks have faded gradually over a few weeks and I need to get 'r done. Given the symptoms below, do you think it is calipers or master cylinder or something else?

1. Place hose on bleed screw, put end in vessel with end under brake fluid level.

2. Opened bleed screw and bled all air out. I had to pump the brake rather quickly to get the bubble to move.

3. Fed a cup of brake fluid thru top, delivered through bottom bleed screw. Took that cup, returned to top and did it again. No air left, absolutely. No leaks in the line anywhere.

4. Closed bleed screw. Zero resistance on the brake handle. Squirts a 2 inch fountain of fluid straight up above the handle, upon compression of handle, from a small hole on the bottom of the reservoir. Upon return of the handle, some fluid flows back in to the reservoir.

What do you think? Thanks for the help.

 

Time to rebuild the Master..

 

+1 They're easy as long as you have a pair of long-nose internal snap-ring pliers.

While you're at it, if you're feeling ambitious you can also replace the sight glass if your is funky.

 

Thanks for the guidance, dudes. I just pulled it off, and the pump seal is wasted.

My sight window is indeed goobered up. Chacal says there is two ways it can be attached. I think it is pressed in, but I need to look at it more closely after I get the electric switch disconnected from the master cylinder body. It's not immediately obvious. The shop manual doesn't say anything useful. Do I just get a screwdriver and pry it out?

 

Ok, I fiddled with it for a while and got the switch out. The U-shaped phlange tipped me off. There is also a hole in the master cyl body where you can depress a retaining clip on the body of the switch. Doing that and rotating the U did the trick.

My sight window was pressed in and very rubbery... popped right out.

Time to order a rebuild kit from Chakal...

 

When you're cleaning the MC, look very closely at the bottom of the reservoir. There are two "partially drilled" holes, one of which has a TINY hole drilled in it. That little hole needs to be clean. I use a bristle from my parts cleaning brush clamped in a hemostat to poke the hole clean.

 

Well, complete success, thank you for all the advice. Following are some more basic things to know for the next guy.

1. When putting on the new seals on the plunger, warm them up so the rubber is stretchy. Otherwise you will tear the seal.

2. You must "prime the pump" by using a vacuum to pull fluid air out of the little hole at the bottom of the reservoir, thereby sucking fluid in the plunger via the big hole.

3. When bleeding the lines of air, you must change the position of the bike from kickstand to the big stand. Otherwise the air will remain.

Viva la Maxim!

 

This is a good habit to get into when doing ANY service work; the bike is a much more stable for wrenching on when it's on the centerstand.

My only exception to this rule is when doing "quick" clutch work; if you leave it on the sidestand and are careful you won't lose any oil.