Xj750 seca master cylinder swap

Hey xj wizards!

I know I've seen handlebar mounted MCs on modded 750 secas before, but haven't been able to find a thread. I'm interested on doing that to mine, as I keep getting air in my system from somewhere (no m/c recharge after stainless, caliper rebuild and m/c rebuild. This'll be the 3rd headlight removal.)

So- what should I use as a donor? Something from an XS? The Maxim? Or are there any fit guidelines? And will braking feel real strange without the slack of a cable? Will be strapping it to eurobars.

I appreciate your input.

 

Just make sure that you use one with the same diameter bore as the original.
I would not assume that the air in the system is the fault of the master cylinder though.
What procedure have you used to bleed the system, did you replace the bleeders, and did you tend to the brake side of the anti-dive units?

Braking will feel better without the cable, but you really shouldn't have enough slack in the cable to notice.

 

Use handlebars and master cylinder from an '83 xj750 maxim

 

K-moe, I bailed on anti-dives after I cracked a housing @ brake bleeder on left side. I've been reverse bleeding (fill mc, then fill rest from calipers till it drips from top of splitter's hardline, hook up, and keep filling another 100ccs or so from each caliper. Pull from reservoir as it fills.) Just want easier access if I'm going to keep dealing with it.

Hogfiddles- thanks man! I'll go digging around for the maxim mc/res.... is there going to be a lot of conflict between euro bars angle and maxim reservoir angle?

 

I was just asking because of the additional places that air can get trapped. Also be sure that you are either using new crush washers, or anealing the old copper crush washers before reusing them.

 

Totally fair, man. A wiser and more motivated shadetree mechanic might find and stop that air leak... needless to say, it's not me.

How does annealing copper washers work? Hit it with the propane torch till it glows, then let cool?

 

Heat them until cherry red, then quench in water.

Also the leak may not be a leak. There are plenty of places for air to get trapped.
Make note of step 10.

What I do to bleed the system.
1. get a large syringe from a farm store and about a foot of vinyl tubing (you can also use a 2-stroke oil mixing syringe).

2. Cut 6" of tubing and attach that to the end of the syringe. Remove the Syringe plunger. You now have a funnel to fill the master cylinder with.

3. Break loose all four bleed fittings (be sure to put down cat litter or drip pans).

4. Tie the brake lever to the grip.

5. Fill the master cylinder and syringe.

6. Wait overnight (or at least a few hours)

7. You should now see brake fluid coming out. Close the bleeders, and untie the brake lever.

8. Bleed the brakes as normal, starting with the anti-dive bleeders, then the brake caliper bleeders. Remove the funnel.

9. You aren't done yet. There will still be some air in the system. The next step cures that, no matter what mehtod you use to fill and bleed the system.

10. Use a vibratory sander (no sanding pad) and slowly run it along the brake lines, calipers, and distribution block from bottom to top. This will move any remaining air bubbles up into the master cylinder. Tap (or vibrate) the master cylinder to get the air bubbles to come out of the return hole. This process can also be done with a box-end wrench or other simmilar tool, and tapping the calipers and lines (it just takes longer).

11. Do one final bleed normally, just to be certain that the calipers are fully bled.

12. Use a flashlight to check the fuid level in the master cylinder. It should be below the fill neck. Unfortunately there is no dip-stick or sight glass on this master cylinder, so unless you empty it and measure out the fluid you will need to just eyeball it. If the fluid level is too high the brakes can hydrolock and not release.

 

Hey everyone! It’s been awhile since I’ve been on here. But now I’m looking into doing this same thing, except. Is it possible to use the master cylinder from the maxim on stock seca handle bars? Will there’s be any clearance issues. Also found this on eBay, Idk if it’ll work, or not, but is it enough to take a shot on it? And will I have to add a new line from the master cylinder to the proportioning block in the triple tree? Thanks for the help, sorry to bring up and old thread with lots of questions

https://www.ebay.com/i/301641850591...8%26rvr_ts%3D9cfeda9c1650ada1e7410351ffdc3cd7

 

Hey there, just sold my Seca. Had to give up riding.
The master cylinders you need to be careful one of the seals that you get in the rebuild kit is too small. It's probably where you're getting your internal leak. If you bought the rebuild kit from here then you're probably good. But if you get the one that's on eBay or the other places it's not quite right.
Also I would recommend getting the spring loaded bleeder screws. Those things were great.
I actually got rid of my anti dive forks. they were pitted and rusted. I put on a set of maximum forks. Everything fit except I had to go to a smaller rotor/s. The maximum it a smaller rotor so I had to swap that out but everything else was the same and no empty dive mechanical issues because those forks did not have them. Big reason I chose them.
Hogfiddles was a lot of help. Also K-moe very knowledgeable I could never have done this project without them. Wanted to give a shout out and say thank you everybody for the help. It was a wonderful project. Almost gave up a couple times.
Steve