Converting from one disc to two discs - what sized master cylinder do I need?

[Wzed]

I am currently running a single disc up front, and want to add a second.  I'm going to use a Berringer MC, and they come in three sizes: 14, 17, and 20mm.  I know 14 is too small, but I'm not sure which of the other two sizes is right for my application.  If 17 will work, is there an advantage to using 20 instead? 

[Howie]

Model? Year? Calipers?

[Speeddog]

Ratio between the lever and piston is not necessarily the same amongst Beringer and Brembo.

Beringer will need to guide you.

[koko64]

I converted my750 to single disc. I basically removed half the system. I purchased a Brembo ps13 "coffin"master cylinder and it brakes quite well with the single oem 4 piston Brembo goldline caliper, oem 320mm disc, braided line and aggressive Ferodo sintered pads. The oem Brembo MC should be much cheaper than the Beringer item. Just a thought.

[Wzed]

Model? Year? Calipers?

From one Brembo axial (not sure which year/model - I think they it came of an S4) to dual Brembo radials from 848/1098.  Ohlins R&Ts with aftermarket radial bottoms.

I converted my750 to single disc. I basically removed half the system. I purchased a Brembo ps13 "coffin"master cylinder and it brakes quite well with the single oem 4 piston Brembo goldline caliper, oem 320mm disc, braided line and aggressive Ferodo sintered pads. The oem Brembo MC should be much cheaper than the Beringer item. Just a thought.

I already have a Berringer clutch MC, so I want them to match.  

[stopintime]

Berringer list their 14mm for a dual 4-6 piston caliper set up, but also that this is combined with their discs (?) We/you/they need to know the combined (caliper) cylinder volume for it to make sense. Plus the pivot to plunger distance.

Since we don't know (limited info available), you have to ask Berringer - who surely know 

[koko64]

From one Brembo axial (not sure which year/model - I think they it came of an S4) to dual Brembo radials from 848/1098.  Ohlins R&Ts with aftermarket radial bottoms.

I already have a Berringer clutch MC, so I want them to match. 

Ah. I get it.

Best to let Beringer know about your caliper type and disc diameter and thickness as has been suggested. They may also have options for "feel" Vs "bite" in relation to MC configuration.
On my M900 with twin 4 pot/320mm Brembos I went from sintered pads with violent bite to organic pads with more feel.

[Wzed]

Berringer list their 14mm for a dual 4-6 piston caliper set up, but also that this is combined with their discs (?) We/you/they need to know the combined (caliper) cylinder volume for it to make sense. Plus the pivot to plunger distance.

Since we don't know (limited info available), you have to ask Berringer - who surely know 

Ah. I get it.

Best to let Beringer know about your caliper type and disc diameter and thickness as has been suggested. They may also have options for "feel" Vs "bite" in relation to MC configuration.
On my M900 with twin 4 pot/320mm Brembos I went from sintered pads with violent bite to organic pads with more feel.

Yeah, I'm going to contact Beringer; they claim that of the three sizes, only the 20mm size is for dual 4-6 calipers (the 14mm is for a single, 2 piston caliper, the 17mm for a single, opposing 4-6 piston caliper).

[stopintime]

I'll repeat: in the bike model specific 'app' they list the 14 for a 1098, 996 and other bikes with two four piston calipers. I wouldn't trust that, but it's either just confusing or a sign that their products are different enough to require some investigation....