1972 XS650 Front Cisc Brake Master Cylinder Repair

[corbshere]

I Can't purchase a 1972 master cylinder (unless you have one I can Buy?!!!) so the next thing I can do to keep my bike oiginal is to install a rebuild kit in it.I have looked at this unit several times and I cannot see how to remove the existing plunger and related parts, has anyone got any experience with this? I had the bike sitting for years in my shed and when I went to check the fluid level I found that it had all dried out and the plunger was stuck "in" It looks like I can buy a rebuild kit on MikesXS parts but I don't see how you get the old parts out. Any help would be GREATLY appreciated!!

 

[yamaman]

gday mate, first off you might want to get a manual, secondly, get a manual! pretty sure, on Mikes page with the master cyl kits, there are circlip pliers, get them because inside your m/c the circlip holds the whole show together. search the tech forum, probably some good help there, also links to on line manuals. cheers

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[cra-z1]

Yep you need the circlip pliers from Mikes. You probably have some rust around the clip. Use a fine needle to dig and scrap any rust/debris so you can see the clip holes. Take your time. I can't remember but I had to modify the pliers for one of my MC clips. It could have been for my z1. Once you get the piston out don't go sticking a screw driver in the bore or anything that will scratch it. Look for corrosoion and pitting. The only thing you can do is clean it up and try a new seal kit and plunger. I was lucky and found a NOS unit on e-bay for my XS2. Good luck

 

[corbshere]

I can see the plunger that is depressed when you squeeze the brake handle ( its stuck in the fully pushed in position). I removed the bolt at the pivot point of the brake handle and it reveals what appears to be a brass bushing that the bolt pass's thru and it is threaded. so I can't see how the squeeze handle will come off untill I remove that bushing! I cannot believe that Yamaha would put such a complicated pivot on the front disc brake handle! The snap ring pliers won't do you any good at this point as the plunger mechanism cannot come out without that handle, and attached plunger pusher, is out of the way. What a freeking chore this seemingly small repair job is becoming. Man I hope I can get this behind me as its just a headache. Am I seeing this thing right, or has someone broke this thing years ago and did this as a non factory repair?
PS- I have a manual and it does not show this repair any where

 

[jayel]

screw the pivot bolt back in part way and use it to pull the bushing out

 

[tadd442]

Mikes advertises a rebuild kit for their "early" mc....not necessarily for the original mc on your '72. It would be awesome if it worked! Hell, its kinda cheap, give it a try and let us know!

 

[pamcopete]

I have 5 motorcycles. I bought them one at a time. The first thing I did to each of them when they came in the door was to rip the master cyinder and brake hoses off and replace with new along with a cleanup of the caliper and new caliper kit installed. All of the bikes have a rock solid feel to the brake lever. When I squeeze the brake lever, the bike slows down dramatically and stops.

I used MIkesXS master cylinder Part #08-0255 for the single front disk brakes and MikesXS Part #08-0265 for my '81 CB750C with dual front disks. These are the very best master cylinders that you can buy. I also installed stainless steel hoses on 4 of the 5 bikes.

My thoughts on this are that it's OK to rebuild the caliper because it is a very simple mechanism and you can see the inner workings clearly. Not so with the master cylinder.

There are other parts that we routinely replace with non originals, like the mufflers, head pipes, tires, seat covers etc. so I don't see why its so important to maintain that OEM look with something as important as the brakes.

Brake fluid attracts water. Water causes corrosion in the inside of the brake components. The master cylinder on a '72 motorcycle is 40 years old. Time for replacement.

 

[corbshere]

It does Make sense Jayel ! and I'm gonna try it next. Tadd442, if I get that bushing out I'm buying that kit and gonna try it (got a long michigan winter stareing at me anyway!)Thats good advice Pete and believe me if it doesn't look "right" when i'm done ....new M/C is going on for sure. I did replace the hoses ,they were weather checked. Thanks to all of you guys!! I REALLY appreciate your time and opinions!!

 

[ThumperMike]

I'm looking for a rebuild kit for my 1975 XS650B. I don't see one on Mike's and the one on 650Central is $82! ANyone know of a reasonably priced solution? I'd really like to stay stock. Thanks!

 

[larksnostril]

Hello.
I'm loving the Pamco ignition!
Got a brake question:I've got a question about '81 special..replaced both front brake calipers/pads and MC...new parts from Mikesxs.already head braided brake lines on. /there are no leaks anywhere..using correct DOT3 fluid
Problem:
I'm almost done with bleeding the system and the front caliper does not consistently release so wheel will run free.
What can cause this and what area my next moves to figure out and fix? One thread said to wash all the caliper parts with brake fluid after dissembling and reassembling...is that something I should done with the new too?
Charlie

 

[tadd442]

I would say that you still have air in the system.

 

[larksnostril]

Thanks for the reply.
I've had to bleed the brakes when braided hoses were installed but this problem with piston not retracting to allow wheel to turn smoothly did not occur. O I wonder if there are other possible explanations as well..any thoughts?