Bleeding disc brakes on a 72 xs1-b 650

bsquared

My manual doesn't show disc brakes for my bike, but it's got them. I just cleaned out the Master Cylinder, but my line is plugged, can't get air or fluid through them. Any ideas on cleaning out the lines and bleeding the system? I haven't got to the point where I can see if the caliper pistons are stuck, but I imagine they are, but that seems like the next step after getting fluid through.
If anyone has an exploded diagram they could post, that would be great!
Peace,
Bsquared

jayel

the fluid has probably crystallized in the lines might try working a wire thru but the easy way would be to replace them, which reservoir and caliper do you have they used several over the years (pics?) once you get the M/C pumping and clean lines it still probably won't have enough oomph to pump out frozen pucks block the line fitting with a plug and pump grease with a grease gun thru the bleeder (clean bleeder first, it's plugged too)

INXS650 · 650Rider Supporter Joined: Mar 22, 2007 Posts: 645

Don't put grease in your calipers! Anything but brake fluid will contaminate your seals. It's a big no no. Do not try shoving wire through your lines, you will puncture the small fragile rubber hose inside. Get new lines, and see if you can get fluid down the the caliper. It will have to be rebuilt though. Most likely it is corroded, and stuck.

jayel

INXS wrote Don't put grease in your calipers! Anything but brake fluid will contaminate your seals.

if the caliper is rusted in place he's going to be replacing the seals anyway he's trying to get it apart

bsquared

I'll avoid the grease. Seems I don't have anything to lose with tyring a coat hanger down the lines, eespecially if the next option is to replace them. I used some powerful tetrachloroethylene brake parts cleaner from Carquest that quickly loosened up the master cylinder...I hope it didn't eat up anything important (including my lungs and chromosomes.) I also have been spraying it on the caliper pistons in preparation for getting to them. If I can get some of this solvent down the lines, I'm sure it will clear them.
Thanks for the advice.
Bsquared

bsquared

I just posted photos of the master cyl and wheel cylinder into my gallery, if that helps with the ID.

jayel

you have the early model 73/77? if you can get the m/c to pump fluid it may push out the lines and pucks, did you clear the little hole under the tab in the bottom of the resevoir?

KYLEPRESTON

jayel are you running dual disk on your 73? I am looking for a picture of where the splitter valve goes. I believe it should mount behind the left (if you are looking at the bike from the front) fork. into those two holes. I can't find info on this anywhere.

thanks Kyle

jayel · Last edited by jayel on May 30, 2007, 10:08 pm; edited 1 time in total

nyah, single disc, it's a 74 TX most of the dual discs i've seen mount the splitter center of front fork then a line down to both sides, maybe someone with a dual setup will post some pics (hint, hint)

www.biker.net/74-76_65...0main.html

KYLEPRESTON

I would love to post something once I have it setup. these older bikes are fun to play with but a pain to setup properly.

thanks though

kyle

Xumi

bsquared wrote:

I just posted photos of the master cyl and wheel cylinder into my gallery, if that helps with the ID.

ine was pretty nasty.. but here's what I did to get my piston out for cleaning...

Cleared the bleeder... with a small nail.. it was completely clogged.

Bled the hell out of the lines (even though I didn't see any movement through them for about 10 minutes, they eventually did bleed), then pumped on the handle for about another 10 minutes and the piston ever so slowly worked it's way all the way out... there was all kinds of nastiness behind the piston but amazingly the seals and piston itself was fine.

Cleaned it all up with alcohol... Put it back together, bled the hell out of the lines again - to the point of making sure that all the old fluid had been changed out about 2x, put the pads on and pumped it to the disc... and the brake is solid as a rock.

bsquared

I can't see any "tab" at the bottom of the MC. I have a big hole, and a little pinhole in line with a little dollop of what looks like solder, perhaps filling some sort access hole, but I don't see any tab.
I pulled the lines off and can't get any wire through, so I filled a listerine bottle with alchohol and curled the hoses into it and will let it soak over the weekend. I'll try a wire again, then maybe new hoses.
Where is the spot on the wheel cylinder for bleeding? Is it where the line goes in?
Thanks,
Bsquared

Xumi

bsquared wrote:

I can't see any "tab" at the bottom of the MC. I have a big hole, and a little pinhole in line with a little dollop of what looks like solder, perhaps filling some sort access hole, but I don't see any tab.
I pulled the lines off and can't get any wire through, so I filled a listerine bottle with alchohol and curled the hoses into it and will let it soak over the weekend. I'll try a wire again, then maybe new hoses.
Where is the spot on the wheel cylinder for bleeding? Is it where the line goes in?
Thanks,
Bsquared

Not sure I understand your question.. Do you mean where is the bleed valve on the caliper? It's a silver nut looking thing with a hole on the end of it on the rear side of the caliper, not too far from where the brake line bolts on.

bsquared

The "tab" was mentioned in an earlier post regarding cleaning out the MC. I just see two holes in mine. I'll look for the bleeder on the calipers. Thanks for the reply.
Bsquared

Xumi

bsquared wrote:

The "tab" was mentioned in an earlier post regarding cleaning out the MC. I just see two holes in mine. I'll look for the bleeder on the calipers. Thanks for the reply.
Bsquared

Ahh - the tab I know about.

In the Master Cyl, there is a plastic piece that runs around the edge of the cyl. On the bottom of this thing, there are two small parts sticking out into the cyl itself.. they are clear and one of them sits just above one of the holes in the cyl.

I can take a picture later tonight if you need.

bsquared

I checked the lines that I had soaking in isopropyl alcohol over the weekend, and was able to push crafting wire throught them tonight! I still never found any clear plastic tabs with hidden holes, put the lines on, loosened the bleeder fitting I found, and filled the MC with fluid. I pumped the handle (never could figure out how to get the brake lever off...seems to have a threaded sleeve that needs to be punched out of the bracket) for 5 minutes and started to get fluid out of the bleeder into a cup (bubbled a lot.) Finally seemed to run out of bubbles, used up a can of fluid (I know it's cheating, but it looked pretty clear so I put the fluid from the overflow back in the MC.) The calipers seemed to work right away! At least one of them. I'm sure if this is kosher, but the brakes seem to be working. All I need to do is to try a trip around the yard on the bike now...maybe down to the gas station (it's still got Illinois 76 plates on it!) and see what happens. I'll need to get a motorcycle classification on my license too.)
I may not have needed to rebuild the caliper pistons and MC after all....
Peace,
Bsquared

jayel

if you have the early round resevoir it doesn't have the tab, two holes is correct, (The calipers seemed to work right away! At least one of them.)
I'd take it all apart and clean it you don't want to chance it locking up on you, unscrew the bolt holding the lever until it clears the bottom of the bracket then pull it and the bushing out, the pistons in the caliper should be removed and cleaned if one side moves but not the other get two pieces of flat steel and a couple of C-clamps to sandwich that side, that will stop it from moving and force the other side out

bsquared

I've got the lever out, but now, for the life of me, I can't figure out how to get the guts out of the MC. The plunger has a rubber boot over it...I turned the plunger about 20 times and nothing happened. I looked into the other end and can't see any screw slot. I'm looking at your exploded diagram and it looks like parts 3-10 come out the plunger end, I just don't know what to force....
I really appreciate your help.
Peace,
Bsquared

bsquared

Jayel, I just went to www.biker.net/70-73_65...0main.html and found the exploded diagram I need and see that there is a mysterious, and probably troublesome, snap ring that I need to remove to get to the guts. It's under the boot, and I just need to get it off. It's already cracked in a few spots, so, I'll just pull it back and see what happens.
Thanks,
Bsquared

bsquared

I got the snap ring off, just took a trip to a neighbor with a well stocked tool box...sure nuff, there was a lot of crap in there. Before I head off to a parts store, I'll break open the calipers and pistons and see what's in there...I'll likely break something along the way.
Take care,
Bsquared.

jayel

sounds like you're on your way I knew it would be full of crud and the brakes are no place to take short cuts

bsquared

The calipers pistons are rusted pretty solid and won't hardly budge, barely detectable. I'll try filling the calipers with brake cleaner solvent, try the piece of wood in the slot w/o the pads and blow some compressed air into it and see if they both break loose. slowly but surely....
Bsquared

jayel

hydralic pressure is your best friend here just pump them out if one side frees up sandwich it like I said and it will force the other piston to move, once you get them both moving you can try air, wrap the caliper in a heavy rag, air will blow the puck clear acrossed a room, not to mention fluid all over

Xumi

Patience is your friend removing those old pistons. If you are getting any piston movement at all - keep pumping.

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