I got a 98C. Just got done putting new bars on. During install(that I worked on slowly over a week). I had my grip and master cylinder on the floor. So yeah, my brake fluid leaked out of the top. I figure at this point, I might as well do a full change of the fluid. Is there a procedure or method to flush out and change the fluid? I only have whats left in the line. Also, how full should the master cylinder be? I don't see any fill lines in there anywhere.

 

Just did mine yesterday, well drained it while waiting for new brake line to come in. You're going to need a 5/16th's clear hose (got 4 ft from ace hardware for 81 cents). A container to dump it in.

You also need a 10mm wrench. Use the closed end. And what you want to do is put the tube over the drain valve, it fits pretty snug. There's a rubber cap on this valve so put the tube on, put the wrench over the nut. Open it up and hold the brake in.you should see liquid coming out. When it doesn't come out anymore, close it with the wrench, leave go of the brake and let it reset to it's standard position. Open the valve again, use the brake and repeat.

From what I hear it's like draining a water bed so you want the container your draining into to be raised up a little bit. ontop of a bucket or chair or something.

These were on my bike so the tools you need maybe different sized hose & wrench etc.

As far as filling? Well I didn't get that far yet. But I understand you don't want any air in the line so I'm not sure how to do that. I'll take any advice as well.

 

i did my 2000 sporty, I would recommend using a cheap syringe. My master cylinder had lots of **** collected in the bottom corners of the master cylinder. I would not want to run that through the brake system. Use the syringe, clean out the master cylinder with a clean lint free cloth then refill and bleed, you have to use DOT 5 brake fluid, it was expensive as **** when I bought it

 

if all the fluid is drained, you need to bleed the system of all the air. This can be a pain in the *** if you dont know what your doing. Its easy enough though, once you do it once you will have no problem. Autozone/pepboys sells a basic bleeder kit, all it is is a clear hose with a small bottle to collect the fluid that is being bled out of the system. The hose is clear so that you can see the air purging from the system. This is how I belled my brakes

Open master cylinder, drain fluid with syringe, open bleed screws on brake caliper. Hook the hose up to the bleeder screw, otherwise fluid will be all over your garage and your wheels. pump the brake to get all the fluid out of the system. Once all the fluid is out, tighten up the bleed screws. (This would be a good time to change your brake pads as well) Fill the master cylinder with new fluid and start pumping the brakes, do not let the master cylinder suck in air, make sure there is always some fluid in there, once you see that the fluid is not being drained from the master cylinder into the brake lines, pump the brake lever and hold, (You might need a buddy to help with this) There should be no pressure. Have your bud open the bleed valve while you hold the brake. Close the bleed valve and repeat pumping the lever. Make sure there is fluid in the master cylinder, you don't want to suck air through there it will defeat the purpose of bleeding the system. once pressure starts to build, you will see air bubbles in the clear hose. Keep pumping the brake, hold, open bleed valve, wait for the air, close bleed valve and repeat. Eventually pressure will build. ...whew....

 

I just open the bleed screw (valve) located on brake caliper very slowly while a friend holds the brake lever. That way the air and fluid just trickles into a rag held below the bleed valve. You don't really need a bleed kit if you do it carefully. Just let a bit come out at a time, then repeat the process.

Close the bleed screw, then have your buddy release the brake lever and do this again until the fluid is clear. Try not to pump the brake handle too vigorously, as it can agitate the fluid and make getting the air out more time consuming.

It's really easy. Also, read the top of the master cylinder and make sure you buy the correct DOT rated fluid. Mine uses DOT 5, but some bikes use DOT 3 or DOT 4. Do not mix brake fluids, could cause brake failure.

John

 

Save yourself a chit load of time / frustration and install a speed bleeder on your caliper. I recently replaced the front brake line on my sporty project bike. Needed to re-fill the fluid and this was a break through (pun intended) for me. Plan to do the same on my Ultra when I take it apart this fall.

 

Bleeding brakes isn't frustrating. I'm not mechanically inclined much and it was probably one of the easiest things I've done so far. I don't see the need for a speed bleeder. Took me maybe a half hour. That's pretty much just a couple of beers.

 

+1 what John said.

 

Great. You can come do mine next time

 

Thanks for the replies guys. Bought a bleeder kit from Autozone last night, only like $8. How about the fill line for the master cylinder. I don't see one. Do you just fill it to the top?