Hydraulic clutch slave diameter?

XsJosh

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I've just installed a hydraulic clutch set up using a slave cylinder from an Aprilla Tuono 1000. I'm curious who's done similar mods and what size master cylinder did you go with. I mocked it up with a 5/8" and that was stiff, I've got a 14mm on now, a little better. Looks like Aprilla used a 12mm master. I want to check tonight and see how much throw I'm getting at the slave, is there such thing as too much? I have not run the bike with it yet, I'd like to know it's all good before I start it.
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Yes, you can get too much travel. You'll hear the pressure plate rub the side cover. I'm using a 13mm master with a 1" slave.
 
I used a long rod from an other xs engine an opened the hole from the stock actuaror.
 

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I like Honda VTR1000 slave cylinders 38mm with a 14 mm master. It looks like a lot of Honda's use the same slave cylinder.They sit closer to the engine case than the Aprilla slaves.
With heavy springs and an Alto 8 plate clutch it feels pretty nice.
 
Use 0.060" (1.5mm) as your max desired pressure plate displacement. Add about 0.005" - 0.010" for slack take-up, for a max travel of about 0.070" for the slave cylinder. Much more beyond that risks the pressure plate uncoupling from the hub splines, and contact with the sidecover.

From that, calculate the target volume displacement of the slave, circular area of its piston times the 0.070" travel.

Then, knowing how far the master cylinder's piston travels, calculate what piston area is needed to get that equivalent displacement volume. Add a smidge to account for master cylinder slack take-up. From that piston area, get its diameter. Choose something close...
 
Clutch feels nice and easy to me. My dad's vfr800 has a heavier clutch, my tiger 800 is comparable. It seems lighter than the stock clutch on the XS, but the stock XS doesn't seem that bad to me.

My slave was a custom piece. It fits where the original worm set up was, fully in the side cover.
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Rr,
Now that is a very nice solution. I assume the master is small diameter as the slave must be small. Could you document the build process or have you already done that? Did you run into problems?

Tt
 
Silly this, but I wondered if a tiny brake caliper off a bicycle could be sawn and ground to fit inside the case. Fine machining, no... Crude machining, yes!

Probably the little caliper would have too little travel but maybe okay.

Tt
 
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