650 Special brake caliper upgrade

Grewth

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The one component of my '78 650 Special that I don't like too much is the single piston sliding type caliper.
What would be a good modern type caliper to replace it with ?
I'm capable of constructing my own mounting adapter so that's not a problem.
My basic criteria is something that will work well and give a more powerful and progressive braking action.
But at the same time I'd like to get something which is commonly available and has readily available pads, seals, etc.
So I'd rather avoid using something from an obscure model with no pattern parts available.
Any suggestions please ?
I'm not building a race bike so it doesn't need to be super powerful, just a worthwhile improvement on the rather spongy XS unit
 
I have and like the Yamaha twin piston blue spot callipers used on the R series sports bikes. The gold spot version
is slightly lighter as it has ali pistons.
I use it with a 10mm master, I dont know what would work with a standard XS master.
Vintage brake have a helpful master caliper ratio chart but you will need to know the size of the pistons in the caliper.
http://www.vintagebrake.com/mastercylinder.htm
 
Yes, if you want to improve "feel" and modulation, you will probably need to change to a smaller master cylinder. Here's that chart Signal linked to. I have marked the stock 650 sizes .....

MC Chart.jpg


Many of us with the later 14mm MC switch to an 11mm one. This gives much better "feel" and progression or modulation but does have more lever travel. I didn't like that at first but have grown used to it. I also tried a 1/2" (12.9mm) MC on my other 650. It gives slightly better "feel" and modulation but not as big an improvement as the 11mm. But, it also has less lever travel.

So, with the smaller MC, a braided stainless line, and Ferodo Platinum pads, I'm pretty happy with my brake. I don't feel a caliper change is needed. I think matching the MC bore size to the caliper piston size is the big thing for improving "feel" and modulation.
 
I have this set up:

https://www.motolanna.com/ourshop/p...NC-Billet-Alloy-Yamaha-SR500-SR400-XS650.html


It works well and provides a nice progressive feel vs the stock set up.

You will need to source a master cylinder, Brembo caliper, and disc, but it is as close to plug and play as you can currently get.

As jetmechmarty mentions above, if you have spoked wheels, you will also need to file or machine the back of the caliper for clearance.
 
I did the blue spot caliper upgrade. Details at Dad's Bike starts at post #23

The only downside is the machined spacer needed for the FZR rotor, the upside is a much lighter rotor that is available (or was) cheap on Ebay.
 
I have fzr discs and spacers I made a few years ago if you want to go this route.

Edit: I just noticed you are in the UK so shipping would probably be an issue.... Carry on....
 
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Many thanks for all the replies.
You've certainly given me something to think about.
As my 650 Special is virtually standard apart from the exhaust and bars, I'm not looking for something that looks particularly "tricked" or modern.
I'll be trying to find something that works well but looks like it could have been fitted back in the day, a period modification.
I don't know if that makes any sense to anyone else, but I've got a sort of thing about keeping things old looking
 
Given that I would bead blast the disc, fit good pads, a braided line (you can get black ones) and use a smaller master cylinder.
 
There's a chance that I might be able to get hold of an alloy Lockheed racing type caliper, if I can persuade someone to part with it for a reasonable sum of money.
Very similar to the Grimeca type mentioned above I think.
I'm planning on using a Special 2 spoked wheel, so I'm not sure that the twin piston caliper will clear the spokes.
Just an idea.
It would certainly look like a period modification
 
The smaller master cylinders I use fit that bill. They look old because they are, lol. They're from other Yamahas at least from the '90's, some even older. This 1/2" unit is from a mid-80's Vision .....

MCFront2.jpg


MCRear.jpg


Another "plus" is the brake line attaching to the front rather than the end like the original did. This allows me to use the cheapo (less than $10) stainless brake lines.
 
For you old gurus I just was planning (already have the parts) on adding a second caliper up front and modern floating rotors to improve my braking.

Am I wasting my time?

I just want some better brakes on my beach cruiser(80 special), especially now that the new girlfriend is down to ride and enjoys it.
 
If you have already bought the parts, in answer to your question.............No not wasting your time.

Keeping the factory MC works well with, and is deigned for a 2 Caliper set up. Stainless Steel braided lines will make it that much better
 
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