Hey guys ive been having a hell of a time getting my front caliper to bleed. I got a chrome 4 piston caliper to go along with my inverted front end since the stock one no longer will work. I got the caliper installed and tried using a vacuum pump to pull fluid in and then do the traditional bleed job with the stock screw. I was only able to get the brake to work if i pumped it a few time but as soon as i let go of the handle it would lose all pressure again. I tried a different master cylinder, same outcome. I installed speed bleeders, same outcome. I sent the brake back and they said there was nothing wrong and it would hold pressure all day on their bench. I got them to send me a new one, installed it and this time i did a reverse bleed, using a pumping and moving fluid from the caliper up. Same damn outcome. I thought before i took it in to the dealer i would see if anyone on here had any thoughts? Thanks in advance

 

What happens if you fill the reservoir and pump the brake? Will it build pressure?

My suggestion is do it the old fashioned way. Fill reservoir, squeeze lever, crack caliper bleed screw, repeat.

 

ive done it the old school way where i fill the MC and pump til it has pressure and turn the screw, close and repeat, with the same out come, no bubbles from the fluid coming out. I even pumped it up and zip tied it and let it sit for hours and it never lost pressure until i release the handle then it instantly loses all pressure. thats what is so confusing about this one, the rear was no problem, and this doesn't act like an air issue (not spongy or little pressure)

 

^^^what he said. Also check all your connections to make sure they're right and not sucking in air. I just did mine and that was my issue. After I fixed that, it was a piece of cake.

 

Zip tie the brake lever overnight and tap the length of the brake line with the handle of a screwdriver several times before untying it. You may have a natural area where air hides along the line. I did this and it hot better but not perfect. After riding for a couple of hours all the bubbles must have vibrated up and out because my brake is rock solid now.

 

Sounds like you are sucking air. Since you changed the MC and caliper you must have a bad line (or fittings), only variable left.

 

I have also found that you have to pump VERY SLOWLY.

I tried pumping it like when doing a car and had the same results you are having...after I went incredibly slow, it worked.

Just takes time...

 

brake line was replaced about 3 months prior to the front end swap and it worked flawlessly with the old brake. i installed the brake line with new rubber over metal washers, there is no leaks at all, all the fittings are new also. Ill try the over night thing because im out of ideas lol

 

I sure would like to see some pics of these forks on your bike, post some when you can if you would

 

and

to isolate the master cyclinder