After suffering a dragging front brake for most of the past year, I FINALLY decided to fix it. Turns out, the caliper cylinders on the 2001 model were stuck due to being gunked up, they would not completely release.

So after cleaning them up, putting in new seals, new pads, etc. now I am unable to completely bleed the line. I have a Clymer manual, and it gives good detail about bleeding the master cylinder and the caliper, but I still have trouble getting the last bit of air out of the master cylinder. I can ride it, but it's a bit spongy.

Any suggestions?
Thanks.

2001 GS500, stock
1977 GS400, purchased new, ridden 28 years
1967 X-6 Hustler, rebuilt from parts in a box in 1969

I've had enough sticking caliper pistons over the past 27 years and 390k+ miles on both Hondas and Suzukis that I've always popped the pistons on my former 97 and current 02 GSs when changing pads, cleaned them up with steel wool or green kitchen pads, and reassembled and bled them.  I fill them as I go and don't wait until the end to start bleeding them.  Riding year around here in NE Ohio splashing thru much salt water does make my calipers more crudded up than most I supose.

On GS front calipers I turn the caliper bore up and fill it over the seal with brake fluid, push the piston in until the seal is engaged, and then turn it with the bleeder up and open it and push the piston all the way in expelling most of the fluid, and close the bleeder.  There isn't much bleeding left to do after assembly is completed.  I don't take the caliper loose from the hose and I throw away the outer dust seals leaving only the inner piston seal.  That outer seal is to wipe the dust from the piston as you push it back in but it doesn't touch the hardened crud I get on my pistons.

With new pads on an old rotor with grooves the bleeding can completely remove the air but the lever can still not feel solid like it still has air until the pads bed in and the lever firms up.

It takes a while to bleed all the air out.Make sure the bleed screw is the highest point.It may require turning the front to the left.Leave the master cylinder cap off until everything is finished and filled up.I gently tap on the caliper,with a screw driver handle, as I squeeze the brake lever.It helps dislodge some air bubbles.

I have an issue now where my front brake isn't working smoothly. It actuates a little, then there's a little resistance, then it goes a little more, then it's stiff again. You can feel it even when the wheel isn't spinning, so don't think it's the pads. Maybe some air in the brake line?

I probably replace the brake fluid in my bike, which I think is Dot 3. Should I go to Dot 5? Do I need to flush completely then refill it all?

Dot 5 isn't compatible AT ALL with Dot3. I asked about it before else where and was told the easiest thing to do would be to buy new calipers, hoses, and master cylinder- then add dot 5. I think it creates a gel like substance in your brakes.

But 12point- your piston in your master is probably just sticking a little. Try pumping it repeatedly while sitting still and see if it gets smoother. If so, it may be time to rebuild and clean it.

Quote from: twelvepoint on August 01, 2011, 08:23:10 PM
I have an issue now where my front brake isn't working smoothly. It actuates a little, then there's a little resistance, then it goes a little more, then it's stiff again. You can feel it even when the wheel isn't spinning, so don't think it's the pads. Maybe some air in the brake line?

I probably replace the brake fluid in my bike, which I think is Dot 3. Should I go to Dot 5? Do I need to flush completely then refill it all?

The GS is spec'd for DOT 4 only.That maybe be why your brakes are a little off. http://en.wikipedia.org/wiki/Brake_fluid