Bad front brakes on my '80 650g

Let me start by saying Im new around here and this looks like a site that will be of use to me. I recently picked up a 1980 xj650g. She runs good, but the front brakes are toast. Ive been doing some research and this seems to be a common problem.

It looks like Im gonna need to rebuild the master cylinder and possibly the caliper. The piston seems to be stuck, however I wasnt sure how much force I should be using.

Is there anything else that I should look for? How can I tell for sure if the master cylinder needs to be rebuilt?

Also, can you guys recommend a good OEM and aftermarket parts supplier? I know bike barn is supposed to be good.

Thanks,

Sam

 

Welcome to the site!

My bike is essentially identical to yours, and over the years I've replaced pretty much everything you've described and can say this: it's worth it.

You can still buy the caliper and master cylinder rebuild kits brand new - likely your dealer can get them -- if not, there's tons available online or even Ebay. Get both. Note that the piston is not included in the caliper kit.

Getting the piston out is a bi**h. Best way I and several others have found is to use compressed air and blow it out -- BE WARNED -- it comes out with GREAT force and WILL cause big owies to fingers in the way!!! Don't ask...

Get yourself a new set of pads, a Speedbleeder nipple, and a replacement steel-braided brake hose now -- you'll thank yourself in the years to come.

I replaced the 2-piece brake line with one 42" long hose with 35° bend fittings from Russell - works perfectly. The Speedbleeder makes bleeding the brakes a snap - well worth every penny - you want the 8mmx1.25 version. Russell and Goodridge both make them.

 

1980 650 Maxim Brake Rebuild Kits

This site has them

 

I read another way to remove caliper piston.

Leave brake line and MC in place. Unbolt caliper from fork. Remove pads.

Place caliper over something to catch oil. Squeeze brake lever gently. Repeat as needed. Remember to keep MC full so you're not pumping air.

 

Thanks for all the suggestions... I see Im going to like this site.

One more question... I dont have much experience working with brakes so this may sound dumb, but if I have the brake line diconnected at the caliper and I squeeze the brake lever, should brake fluid come out? Im assuming it isnt because the master cylinder needs to be rebuilt..

Thanks

Sam aka the husky bear

 

Anywhere you disconnect the brake line fluid should come out, even without working the lever.

Even a bad master cylinder will push fluid through an open line. If you're not getting any you either don't have fluid in there or you are plugged up.

 

Well, I drained all the old nasty fluid and put some more in there the other night, so I know thats not it... so Im definitly gonna have to replace the brake lines correct?

 

As I said - I'd do the whole thing now and save the hassle in the future.
Definitely sounds like you need to rebuild the master cylinder, and as for the lines - I think 27 year old basic rubber lines are pretty much done after all this time, insides are probably pretty corroded/degraded.