cbr250r front brake

[Seraph]

Well, the cbr arrived yesterday and appart from fuel pissing outa the filter when i got it home, it's all good, except the front brakes :| they feel so weak compared to the balius's, You pull in the lever...and nothing happens...you pull it to the bar and you sort of feel it...on the balius you pull it and your thrown forward in the seat, is this kind of weak performance on the cbr usual?
I can't see any problems with the disk or caliper (had it the brake shoes out and both pistons are working) cleaned all the muck off the disk and shoes...yet still no improvement. Iv'e even taken it to a bike shop and they told me it was most likely a seized piston, but it can't be 'coz they both work! arg!! it's not the brake fluid either..they checked that at the shop just incase (like i'm that dim..)
Does this sound like a brake line problem to you??
Any ideas?

[imdying]

Strip the caliper, clean the pistons, replace the seals, they may be a little sticky, and it's good practice to keep them clean. The seals are available from Brake Specs Timaru if you give them the pistons to match the size to.

Replace the pads, they may be contaiminated. Ask Brake Specs, they can probably get them from Darbis if they have an account there.

Replace the brake fluid, because the caliper is in bits and fluid is cheap.

Lube the end of the master cylinder piston, where the lever meets it, with a little dab of grease. Don't get the grease everywhere. This will reduce the friction at that point. Lube the lever pivot whilst you're there.

Report back here :yes:

[Seraph]

$$%& it!!! Tried to do that and couldnt get the 2nd piston out, so took the caliper off anyways and hadd a look, not too bad, cleaned the 1 side i could and put it back on attached everything, went to refill it with fluid, and nothing came through whatsoever, the resoviour(sp?) in the master cylinder stayed full, and the lines & caliper remained full of air no matter how many times i pulled in and released the brake lever..am i right in thinking that when you do that the fluid is mean to be sucked from teh resevior and pushed down the lines??

[imdying]

To get the other piston out, take one out, remove the seal, put the piston back in, pump the other one out, slip the other piston out. Done.

You will need to prime the master cylinder, do a search, the process has been described a few times.

[Seraph]

Well I've done a search on google, and tried to follow a guide i found http://www.dansmc.com/hydraulics.htm <-- here, But no matter what i do, theres no pressure in the lever whatsoever and no fluid is being sucked through from the resevior into the master cylinder.....

[riffer]

Sounds like a blockage in the master cylinder or in the actual brake line.

Do you have an air compressor? I've had this before and used the air compressor to blow the shit out of the lines (after detaching from the master cylinder.

You need to isolate the brake lines from the equation, then work on the master cylinder.

[Seraph]

Unfortunately I dont have a compressor, I think it may be the master cylinder, I had the lines off yetsterday and the whole lever, master cylinder assembly on the bench, filled it up with brake fluid..pumped away and nothing came out..
What can I do about this?

[imdying]

Unfortunately I dont have a compressor, I think it may be the master cylinder, I had the lines off yetsterday and the whole lever, master cylinder assembly on the bench, filled it up with brake fluid..pumped away and nothing came out..
What can I do about this?
http://www.kiwibiker.co.nz/forums/showpost.php?p=607197&postcount=10

If the master cylinder isn't primed, it'll never pump fluid. Period.

[Seraph]

primed it, filled up the caliper and break line from the bleed screw, attached it to the master cylinder and! still not working :| lever pulls in with no pressure. :gob:

[imdying]

primed it, filled up the caliper and break line from the bleed screw, attached it to the master cylinder and! still not working :| lever pulls in with no pressure. :gob:

Clamp the line off with some pliers. Don't butcher the line... protect is somehow, maybe put a little plastic inside the jaws... maybe a chopped up coke bottle.

Then try the lever again. If the lever comes up good, you've got air in it still. If not, the master cylinder is most likely not working correctly.