front brakes

I just installed a used master cylinder on my bike and hooked up my front brakes. I filled the master cylinder with brake fluid and pumped the handle several times. Nothing happened. The brake fluid level didn't even drop. What did I miss? I am a newb when it comes to motorcycle hydraulic brake systems and I am stuck on this.

 

You need to open the bleed screw on the caliper (attach a piece of line first, submerge the other end in about 2" of fluid in a bottle or other container) then slowly squeeze the lever; close the bleed screw when the lever pulls back nearly to the bar.

Release the lever, pump gently a few times, repeat. Be sure not to let the reservoir suck wind, or you'll have to start over.

Do this until no more bubbles come out at the caliper end. You may have to dump out the jar of brake fluid. DO NOT "re-use" fluid, even that you just pumped out.

This is called "bleeding" the brakes. If this doesn't work, then it's very possible your used M/C (or the caliper, or both) need to be rebuilt, or at the very least, thoroughly cleaned and flushed with new fluid.

 

You must determine if the Master Cylinder is working OK.

Wrap the Caliper Bleed Screw with several layers of Teflon Tape.
Puncture the Tape to allow fluid to pass through the Orifice.
Install the Bleeder.
Attach a tight-fitting hose to the Bleeder.

Having a One-Man Brake Bleeding Hose helps.
You can observe the One-way valve.

Pump the Brake Lever.
Open the Bleed Screw and Pull the Lever.
Pump the Lever until Brake Fluid exits the Hose.

If the Brake Fluid is NOT Pumped down to the Bleeder, ... Brake Fluid is NOT being PUSHED OUT from the Master.

The Master Cylinder Seals should pump fluid.
If the Fluid remains static in the system ... the Hydraulic Seals in the Master Cylinder Bore are in need of renewal.

(A SURE Sign that the Master Cylinder NEEDS New Seals is this:
If there is a FOUNTAIN of Fluid rising in the Master Cylinder Bore
when the Brake Lever is grabbed ... The Output Seal is NOT applying Pressure to the Brake Fluid OUT of the Cylinder and the Rear Seal is forcing Fluid back-up through the replenishment hole.)

 

Because of the way the master cylinder mounts on 650 Maxim handlebars it's very difficult to bleed.

It helps to turn the bars all the way to the left. Then you'll probably need to bleed the air out of the master cylinder by slightly loosening the banjo bolt and SLOWLY pulling the lever (lots of paper towels under it when you do this). Snug the banjo bolt before releasing the lever. Repeat until you get fluid oozing out. If you don't in 4 or 5 pumps your master cylinder has issues.

If you read the above carefully you'll realize that 3 hands are quite handy for the procedure. Get a helper if you can.

Then once you have fluid at the banjo bolt you can finish bleeding as Rick and Fitz described.

 

Knowing that what you need to do can get messy; get prepared for a mishap.

Drape a small towel over the front of the Gas Tank.
Masking Tape it from moving.
Place a layer of Aluminum Foil ov er the Towel.
Cove the Foil with Newspaper
Then lay an ugly Towel on top.

Now, ... IF you do spill Brake Fluid, ... you got several layers of defense against getting it on the Gas Tank and messing-up the Paint.

 

What Rick's trying to say is that brake fluid is VERY hard on paint and plastic parts. If it's a rattle can paint job brake fluid will wash it right off. OEM paint lasts a little longer.

 

Thanks for the help so far guys, I figured it was a bleeding issue of some sort. I am at work tonight until 2am and was looking forward to doing this as soon as I got up in the morning before I had to come back in.

My supervisor just informed me I have to be back in early tomorrow to cover the other shift. I guess I won't get to try and fix this until at least Sunday now.

I will report on my progress, thanks again.

 

Bleeding the breaks can be a PITA without a vacuum bleeder.
I did a 'reverse' vacuum bleed with great success...
http://www.xjbikes.com/Forums/viewtopic/t=19604.html
scroll down a bit and you'll see what I'm talking about. Cost me $3.00 canadian, was alittle messy but not too much, and breaks were done in 10 mins. ^^