Goofy front brakes on XJ750

[Pat Kelly]

Wife bought herself an 84 XJ750. It's been sitting for many years.
One of the problems is the front brakes, they won't release pressure. I'm guessing it's the same as our "spooge hole syndrome".
To complicate things, Yamaha was smoking something when they designed this system.
You pull the front brake lever, which pulls a cable, that goes to the master cylinder, mounted under the gauges (behind the fairing). Out if the m/c are 2 metal lines that connect to the right and left flex hoses that go down to the calipers.
But it doesn't end there!
Another flex hose comes out of each caliper and go to a valve body on the bottom end of each fork leg. I'm assuming this is an "anti-dive" feature I remember reading about back in the day. I also remember reading that most didn't like it and by-passed the system (not sure how).
I am tasked with repairing her brakes.
To simplify things I'm considering getting the Parts-n-more master cylinder (like I have on my E and LG) and two long hoses from m/c to calipers. Then bypass the anti-dive.
Has anyone had experience with this "Rube Goldberg" brake system? If so, I could use some insight.

[dbeardslee]

I've got no experience with XJ750's, but I did find a thread on XJbikes.com that dealt with the issue. It says there's a tiny little spooge hole in the master cylinder, and also covered a couple other potential causes - XJ with locked front brakes.

To me an anti-dive feature sounds like a good thing. Wish I had something like that on my XS. It likes to do an impersonation of Bobby Mackey's mechanical bull every once in a while.

[Pat Kelly]

Got the fairing off, can actually see the front master cylinder now. Can't access the screws to remove the cover, but I can see it.
So, cable from lever to master cylinder. Steel hard line to a splitter block. Two steel lines to brackets, transition to flex hoses to calipers. Flex hoses from calipers to lower fork legs.
So much for K.I.S.S.
Rear brake is a drum brake with adjustable rod from brake pedal. Old school.

[Pat Kelly]

The "spooge hole" on the XJ750 looks easier to get to than the XS1100, sort of. At least I won't have to remove the plastic/chalk resivoir to get to the hole.

[dbeardslee]

I couldn't find much info on the XJ750. Are you sure that's not an '83 XJ? I didn't see any XJ's in '84 on the Yamaha parts fiche. Speaking of which, the fiche is sometimes helpful - particularly when you can't find anything else. Wish I could help you more, but it's terra incognita for me.

Might be worth checking XJbikes.com. Probably got more expertise there for that particular bike. JAT

[Pat Kelly]

Got the fairing off, also removed the gauges.
I now need to find my offset phillips screwdriver to remove the m/c cover.
Heading to Nebraska so it will have to wait until next week (when 3 week vacation starts).

[mlew]

A bike sitting for a long time will need some work on the brakes. I would bet that your calipers are stuck also. It would be a good idea to rebuild the MC an calipers. After many years there will be water in them and some corrosion, thus stuck calipers. I would inspect the rear shoes also, old shoes are prone to delamination. Corrosion between the brake pad and backing will loosen the pad and make it come off. A dangerous situation when that happens while you are riding, the rear wheel will lock up.
XJBikes.com is a great resource for parts and tech tips. I am a member there also.