Can't get pressure on front brakes after rebuild. Help.

1981 XJ 650 Maxim

Well, I've rebuilt the front caliper, and cleaned out the master cylinder. The seals looked fine and the bore was relatively clean with a few scapes near the bottom. Both small holes are free and clear.

I installed a new custom brake line and did away with that junction block on the fork brace.

I've got all the bubbles out of the line using conventional bleeding methods. For the life of me I can't pressurize the system. I must have filled the resevoir up 3 times for the amount of brake fluid I've bled through the lines. No bubbles at all anymore.

It mast have something to do with the master cylinder. I may resort to just getting this.

http://www.mikesxs.net/mikesxs-chassis. ... ory_id=1.2

a new master cylinder kit.

Any suggestions before I buy a new one?

 

The master cylinder rebuild kit is worth it, IMO.

I had a very similar issue to you, and it was the seals in the MC - they'd push fluid down for bleeding, but they wouldn't take any pressure at all.

Note - this can happen if the MC was left dry for an extended period, and the seals dried and shrank. If you've got fluid it in and let it sit for a day or so, it might rejuvenate the seals.

 

Hmm, just the kit or should I get the whole master cylinder. It's pretty ugly looking on the outside too! LOL

Well, it sat wet for about a year, but the mess inside was nasty. I think I'll go with the whole cylinder. I'm worried those scratches inside the bore may be an issue too.

Do you know if the master cylinder for the XS's will fit the XJ's. They look identical in the pictures.

 

DanP.
According to this ref program I have it's the same as the XS1100LH and some of the early 750 Virago's. Think I'd double check though just in case.

Mick Faighaigh.

 

I'm told that their Part #08-0255 is a near perfect replacement for our bikes, not bad for $69 US

 

I had the same problem with mine. I bought a rebuild kit and accidently scratch the piston and didn't notice. Had so much trouble trying to get any pressure at all. Bought another rebuild kit after taking it apart and finding the scratch on the piston. Pain in the ---

 

I ordered a maser cylinder from mikesxs.com (just like the one your talking about) and it fit on my bike great! It looks a lot nicer too. It was as simple as just plug and play. It came with new wires to run behind the headlight and a new bolt and washers to attach the brake line to it. I love having a sight glass I can see too. Well worth the money. They ship superfast too. They're in the Tampa area and I'm in Chicagoland. I had it within 3 days with standard shipping.

 

Yup, placed my order with Mikes xs and he's already shipped it. At least I'll solve one problem. Now onto those darn carbs.