Front Brake System Question.

Im going through a 82 XJ650J. Working on the front braking system I cant get the piston outta the caliper. I know the bleader valve is a little crushed but not enough to prevent bleeding the line. when the line is blead Im not getting any pressure at the lever. Is that normal? Im thinking a seized piston, but then again if Im not getting pressure maybe the MC needs a rebuild, but Would I still be able to bleed the line if the MC was shot?? Enough to get the fluid through but not enough seal to create the needed pressure? IDK, havent worked on cycle MC's much.

All banjo bolts are tight and copper crushes are in place with no leakage.

I plan on getting a grease gun to try to get the piston out. I already depressed it 1/8 inch with a C-Clamp and still no movement.

Thanks.

 

Welcome to the site. You need to rebuild that master cylinder - I suspect its never been rebuilt in its 30 year life and its probably long overdue. Kits are available from XJ4ever. Once you've done that, we can proceed further.

 

Thanks. another question....rebuild even when the MC isnt leaking? Im guessing there might be other things going bad besides the main seal then. Would that be correct?

 

Not sure at this stage but brakes are not something to mess about with. A leaking MC is not the only reason to overhaul it. Once we've got a clean slate we can diagnose your problem in a logical fashion. You should also budget for a caliper rebuild as we'll be on your case about that next :wink:

 

OOPs, too late.

THE RUBBER PARTS ARE 30 YEARS OLD.

That is all the reason needed to rebuild the brakes. The factory recommended the caliper and M/C seals be replaced every two years; and the brake lines every four years. Even accounting for a certain designed-in safety margin, you're waayyy overdue.

You can't work on one component and not the others. Rebuild only the caliper, the master will misbehave. Rebuild both and you could pop an original line (they deteriorate from the inside out, you can't see it coming.)

Thirty year old brakes simply need to be serviced, that just all there is to it. We really shouldn't call this a "rebuild" since all that we're doing is the service that should have been done all along.

Now, about that rear brake: http://xjbikes.com/Forums/viewtopic/t=15874.html

 

Len Chacal @ xj4ever has everything you need to do this job properly....it probly needs doing badly!

You'll be amazed and maybe a little shocked at what you've been risking your safety on.

 

I replaced my original brake lines on my low milage XJ550. They looked servicable and did not leak, but I took these guys advise and changed them. When I got them off I could see how bad they were. The rubber lines were very soft. I went with new stainless steel lines made from much better compounds than the OEM lines. After a master cylinder and wheel caliper rebuild all done at the same time I now have very effective and smooth front brakes. Bleeding was easy and my brakes are awwesome. You won't realize how bad they are until you dig in!

 

I had a guy stop over last evening to purchase a sidestand for his bobber he rode over to show me. When I first glanced at it, overall I was scared to even look at it let alone take a chance and ride the thing because it just looked dangerous. Then he tells me it doesn't even have front brakes.

Wow. There's no way I would even bother riding it like that without front brakes. jeeeez

 

Thanks for all the replies. Ill add MC rebuild to the list. I already planned on rebuilding the caliper as I believe it was leaking. I really want to know what this caliper piston looks like before I order the first batch of parts.

I posted a couple mos. back that I was working on this Bike for my fiance. The bike hasnt been on the road in 3yrs. After finishing school a few weeks back, I worked on a DelSol for two weeks then cleaned up the garage for a week to have a good environment to start working on this 650. I just started it this week and so far havent seemed to make as much progress as I hoped.

I already went through the back drum and looked for delamination. Thanks to you guys I knew to even look for that. The pads and drum were glazed but in good shape. I evenly scored them at 45and135, cleaned up the axel with wool, packed 2 outta the 3 bearings, and put a tiny touch of grease on pivot points in the drum, camshaft, and washer plate.
I gotta pull the rear drum cover off again though.... after getting the tire mounted back up I notice I put the brake camshaft back on wrong so now the wear indicator points down ..



@Moellear I'd never ride a machine without a front brake. Thats a moronic old school weight saving idea. So when he pulled up, did he lean it against a tree?? hahaha
btw. Im very tempted to sell my bike and bob a maxim. I like the way some of them look.