Master cylinder upgrade

XJ550H
I am planning on going to dual disc. I am about to start rebuilding current Master cylinder.
have yet to buy parts.
I understand I will have to go bigger on the mc for the dual discs.
can i use a mc from 1981 82 Yamaha XJ650 for my current single disc in anticipation of the upgrade?

 

Well, I'm just curious about how you plan on installing 2 front disks onto an American bike. Are you buying European forks or something?

 

first option is to buy seca forks, 650 I have read will fit
my front tire has a plastic cover on right side where the second disc will bolt on when I do my wheel bearings I will see if they are threaded. I will have to reasearch the fork change.
I know european models did have dual in the 550.
wouldnt hurt to have a little extra stopping power in the mc if I cant convert.

 

Well, post pictures as you figure it out. I'm all curious.

 

what are you curious about ? I will post the pic of the wheel holes.
it looks like I will have to get lower forks from Europe.
i have collected a lot of data about tube diameter from the forms.
I do have a spare disc

 

Keep in mind that you will also need to get the euro brake calipers - they are unique to that model. The one US caliper is not the same as either one of the Euro ones. Also, I have no idea how available brake pads for those calipers are in US.

 

I believe the 550 Euro calipers are the same as the US version 550 models (need one from a Maxim and one from a Seca, or just a pair from a 750 Seca or XJ1100).

 

Yamaha parts numbers said otherwise. I suppose they could be same part with different numbers, but I have no way to confirm that.

Euro spec:

Tube,outer 1 clear buffing
4G0-23126-00-38

Tube,outer 2 clear buffing
4G0-23136-00-38

Caliper assy
4L3-25810-30-00

Caliper assy
4L3-25810-20-00



US spec:

Tube, Outer 1 CLEAR BUFFING
4U8-23126-00-38

Tube, Outer 2 CLEAR BUFFING
4U8-23136-00-38

Caliper Assembly Right
23W-25810-02-00

 

i can see that this would work.
so to modify my original question can i use a 750 seca or xj1100 master cylinder now on the standard xj550 max brake system?
i ask because I am going to be rebuilding my current mc, can i use a 750 or 1100 mc with current set up or would that cause me any problems?
just preplaning this is going to be this winters project.

 

wheel photo there are bolt holes under the cap i put 4 bolts there

 

The caliper assemblies are the same, trust me on this one! There may be minor cosmetic or other differences, but they are fully interchangeable.

XJ750 Seca m/c is a "remote mounted" m/c and you definitely don't want to use it.

XJ1100 m/c is a small bore, designed for a single caliper (the front m/c on the XJ1100 models only operates the left front caliper, the right front caliper and the rear disc caliper are operated by the foot pedal). So you don't want that one, either.

You want a m/c off a XJ650RJ Seca, XJ700, or 1983 XJ750 Maxim. The XJ650 Turbo m/c will work, too, but it has all the inner guts to work with a low-fluid-warning system, which you won't need/can't use.

Or just use on of our big-bore replacement m/c, it's oriented correctly and big enough to operate dual-caliper bikes.