Front Master cylinder question

[icepick]

just got my front brake pads installed, and now the caliper won't build pressure, the pistons or not bound up, and there are no visible leaks, while looking in the master cyl., i noticed the little rubber diaphragm doohickey, has an "X" looking cut in it, could that be the reason it not building pressure?
thanks

[Julien D]

Sounds like it needs to be bled. Biggest pain in the arse ever. I usually take the whole setup off the bike and hang it upside down to try and get the air into the caliper.

[robertotjr]

I changed the brake fluid last week and spent around 4 hours trying to give the system normal pressure again. You just have to be patient and I mean really patient, and eventually it will work.

[Dekon]

Maybe you'll get lucky and have the Brake Bleed Fairy show up like I did. I needed a new master cylinder as the lever mount snapped off. I replaced it and tried to bleed it, never got it firm. It got to cold outside to work on the bike and let it sit all winter covered in the garage. Low and behold I went to get something in the garage and just for fun pulled the lever, it was firm and solid. But like the others said, a total PITA just takes time. Now if the Fairy would only visit my rear brakes.

[icepick]

Tried the patient route, got a little pressure, I have a feeling that there is a pin hole in the line.

[bufftester]

the little x shaped cut is supposed to be there. Bleeding the KDX is a pain in the ass. If you have a Mighty Mite (brake vacuum pump) it goes pretty quick. The method I use works well and doesn't take all afternoon, but is easier with 2 people.
1. Take the cap off the MC and hook a drain tube to the bleed bolt put the other end in a small container (empty soda bottle works good) and put some clean brake fluid in the container so that the end of the tube is submerged.
2. use some tape to keep the brake line below the MC (the big loop of hose at the handlebars needs to be below the MC or you'll never get all the air out.
3. Fill the MC with clean fluid.
4. Here's where a helper really pays off...have the helper pump the brake lever (will need to pump A LOT if the lines are empty).
5. repeat the following: Open the bleed bolt...helper squeeze the brake lever and hold...close the bleed bolt...release the lever.
Keep the MC filled up, after a few minutes you should have fluid moving through the lines. bleed till you get clean fluid and no bubbles.

[TexRex]

Speed Bleeders are a godsend, they make bleeding a one person job.
http://www.speedbleeder.com/