front brake won't pump up

[rda]

Hi,
01 ktm 300 exc; front brake worked fine when i put it up after a 100 mile enduro, bike sat about 2 weeks, now it won't pump up.

at first it was just real mushy, lever would pull all the way to handlebar, but there was a little resistance.

so, i checked the fluid, it wasn't low, then i tried to bleed, no air bubbles, and still wouldn't get any better. I then took master cylinder apart and cleaned, still won't pump up, now it is even worse. i tried bleeding for about 2 hours, even tried forcing fluid back up through the line like you do for the clutch, also bled at the banjo fittings.

any ideas?

thanks

 

[Jaybird]

Blown master seals?

 

[TR]

rda, it is possible you still have air in the brake system. Remove the master cyclinder cover and loosen the caliper. Try pushing the brake pads all the way back into the caliper and start pumping again. Pushing the pads may expel the last bit of air, if that is the problem. It is probably best to try and bleed the brakes using a friend.

Let us know how you go.

 

[rda]

I even took the caliper clear off and used a c clamp to push the pistons all the way in, alot of fluid came out of at the top, but still wouldn't pump up

 

[CagivaWMX]

I had it happen to the rear brakes on my 01 125 SX and heard a few other guys having the same problem, you need to get the Brembo repaid kit, I think it was around $35, it replaced the seals and other parts in the master cylinder that went bad.

 

[SFO]

I put a japanese master cylinder off of a yz onto my 200 and the feel at the lever improved.
I would recommend it.

 

[nate_z]

This has happened to me on my 02 400 sx a couple of times and the fix is quite simple. You have to remove the caliper, take compressed air and blow the pistons out of the caliper. Dirt gets stuck on the seal lips and allows mushy brakes. carefully take out the seals and clean them and their grooves and back bleed the brakes and make sure when you bleed the brakes you push the brake hose below the master cylinder and you will have stiffer brakes then ever. Works for me!