R100Gs replacing master cylinder - what size?

[newguy]

So I just bought an accident damaged bike, 1989 R100GS. It needs a new front brake master cylinder. It still has the original brembo caliper on, what size MC would you suggest for best performance? std is 13mm??

 

[Thunder]

Standard is 13mm, personally I'd stay with that, if I wanted to "improve" braking I'd change the caliper, disc or both.

 

[Kenny]

As the spare parts man states, 13mm is standard

 

[brassmonkey001]

Let's be seeing some pictures of this damaged beastie then.

 

[newguy]

Thanks, I think I will stick to std then.

Will post pics soon

 

[Beemerboff]

A 12mm will give better feel and power, but they are hard to find.

Guzzis used a 11 mm M/C with two similar calipers with no problems , and some folks have been known to sleeve down 13mm cylinders and fit the piston and seal from the 11 mm Guzzi M/C.

Properly set up you wont notice the difference in lever travel , but it can be difficult to achieve - most modern M/C assemblies have a adjustable lever which makes it easy.

Pads make a big differeence too - Lucas/TRW make a modern pad for the OEM caliperwhich is reputed to work well and Vesrah pads are good and cheap if you end up with a later caliper.