Front brake master repair help

[SLB1963]

Had some time today so I took apart my front brake master assembly. When I opened the resevoir it was dry. The bike has sat up awhile. I took all the parts out and cleaned them. There were no holes,tears or broken peices. They were very dirty but in good condition. I cleaned everything with fresh brake fluid. I assembled them cleared the lines with air and put it back together and now I can not get the fluid to pump to the lines. It is not leaking anywhere and just a few bubbles come from the hole on the resevoir. Is there something I need to do since the system has been dry and not working for awhile. I have a 1981MS. I know I can buy a kit but i am not sure it will help. I thought I could clean these up and get them going because they look good. Any suggestions?

[bikerphil]

You'll probably need to 'bench bleed' the master. If you remove the banjo bolt, hold and release your finger over the hole while pumping the lever until the pressure builds up. Then hook the line up and try bleeding. Also possibly the lip on the plunger cup has flipped over from pumping the lever too far. Cover your gas tank and any painted parts with somthing as brake fluid will damage the paint.

[James England]

If you do search of th threads on the forum, you'll find this one is well covered. There's a small spooge hole that needs cleaning. Also, there are various methods of getting the fluid to go where it should. I always do small fast, little jiggles of the lever followed by a pull and hold it... undo bleed nipple. Tighten up again and repeat as much as necessary. It doesn't seem to work at first but it gets there in the end. Have a look at all the threads....people use various methods but I've always had no problems with the above...

[tom clisham]

Bleeding


Don't give up on your MC. these things are a PITA to bleed.
Make sure your handlebars are as high as they'll go while you bleed, ( & still have level MC).

I
watched avideo on youtube of a bike mechanic who kept tapping the bars with a rubber mallet & squeezing the brake handle. I did it & got more air out than any other way. tap the line junction & the calipers as well.

Some times just sitting overnight will allow some air to rise to the MC & you can tap more out. It's a slow process.

Trying to push it out the caliper is fighting the normal tendency for the air to rise.

GOOD LUCK!

[SLB1963]

Got up this morning to try it some more and I can not get any fluid to go to the lines. I treid unhooking the brake line fron the MC and I can get very little pressure on my finger but no fluid, How much pressure should I be able to feel. Today I do not see any air bubbles rising through the MC. It is not leaking at all it just seems that it will not pump the fluid. Does this mean I need a kit??? Mine looks good but I do not know how much fluid it should be pushing with each pull of the brake lever. I have tried all the suggestions so far. If I leave it to sit should the bleeder be open and the lever tied to the bar? My 1st dealings with disk brakes on a MC.

[petejw]

hi slb,

u should be able to get enuff fluid that it should
spurt out, did u put the seals back in the proper way
when assembling the mc?

[SLB1963]

Yes I did. On my 81 MS it has only 2 rubber seals. one on the end of the spring and one on the piston shaft. I took it apart 2 times to make sure I did it right, I still could have messed up somwhere. I know now it should be able to squirt fluid out of the MC when working right. These are the original seals I know they are old but are still soft and look great.

[natemoen]

When you are bleeding the system if you pull the handle in too far the seal inside will often flip and then you can't build pressure. When it flips you need to disassemble and put the seal back on correctly. No more than half strokes of the brake lever to be safe when bleeding.