I intend to improve my front brakes over the coming holiday period with a new front master cylinder and braided hoses. I fitted new discs and pads earlier this year , but this only highlighted the need to replace the master cylinder.

 As I am not interested in going all things k1100 on the front end, I have three questions.
 Obviously my Master cylinder size is standard 13mm 

1. Has anyone fitted the 16mm unit BRA02365 from motorworks , or the 15mm unit BRA 14022.
the latter 15mm listing  says it is for the  R100r Mystic  twin disc unit.

2. Would the 15mm unit give enough feel for the standard k100 brakes.

3. Would the 15mm unit  be enough for the twin pot Brembo calipers that  someone ( I cannot remember who ) fitted to the standard k100 forks, and Suzuki discs, should I decide to go down that route.

Thanks guys

I fitted a 15mm front m/c (from a Suzuki Bandit 1200, as it happens) and it made bugger-all difference to the standard setup. I think it was TWB who went the whole hog.

It was I who fitted a 20mm master cylinder (throttle assembly, acc cable & 35mm TBs from a K1100) on my K100 using 292m Suzuki discs and R1100GS four pot Brembos. I like the progressive and quite powerful 'feel' of this setup which is standard issue on any K100-16V, K1, K1100 or R850/R1100 series Beemer.

The R100R/Mystik do use a 15mm MC with essentially the same callipers as the K11/R11/R1150 & K1200 (early, pre-servo models) and they seem to do the job alright. On my Airhead I also have four pot Brembos (on K100 forks) and utilise a (rare, round master cylinder reservoir) 16mm R65 MC with good result.

Thanks for the replies guys,
having bought new discs all round less than 10k ago,  I am a bit reluctant to go down the route you have TWB, having spent decent money already, although you must be really pleased with the results.
 
I wonder whether anyone has replaced the master cylinder with an original 13mm unit , together with new discs/ pads and hoses etc, and felt the braking was good enough without tweaking anything else.
Would I gain much from fitting the 15mm M/C ?  and how would it change the feel at the lever?

As you have said Dai, maybe the small jump from 13 to 15 or even 16mm, is not enough for improvement whilst using the original 2 pot calipers, but 20mm is, on the four pots. 

Would the 20mm from the 1100 give any advantage whilst using the 2 pot calipers...

I am not a speed freak , steady on the corners and faster on the straights, but I do need to update my 27 year old hydraulic system,  especially with a set of 1100 throttle bodies on the bench ...

Thanks again guys.
Bob

G'day Bob, On my 75 , went down from 13mm to 1/2" by having a sleeve inserted ( a minute decrease I know) and it made no difference. The biggest difference in braking was when braided lines were fitted - chalk and cheese. Cheers Tom

As Tom says, braided hose. That did make a difference. I coupled it with HH-grade brake pads which helped again. I'm also running cast-iron discs which, if you can stand cleaning the mess off the wheels once every couple of weeks, is an improvement over the OEM stainless. They don't ridge like the OEM ones either.

I am running HH sintered pads all round but are very grabby with little feedback due to poor Master Cylinder and poor hoses.
I wonder whether anyone has fitted the Motorworks item BRA 02365 16mm master cylinder to a k100 handlebar . 
The bigger diameter must improve what I currently have, and be good enough to use on a four pot set up as TWB has stated, should I decide later to fit 4 pot calipers . This will my choice if the 16mm unit fits, otherwise I will stay with the 13mm standard unit.
Thanks for the input guys.
Bob

Keep in my for future reference that if you're contemplating using four-pot Brembos over the standard 285mm discs, they do not align correctly and you'll have to fabricate spacers (or machine off the extra bits from the mounting tabs with the 10mm flanges), unless you've got K11 forks, then you'll need the three spoke wheel and 305mm floating discs. It's a can of worms, and a helluva lotta fun!

Not having the luxury of another bike to run whilst mix and matching, I will go with the standard set up of 13 mm on the front with braided hoses and new pads . 
I have steering bearings,  1100 throttle bodies, and a beefier alternator to fit  over the winter, so less time with the spanners and more time riding, means keeping things simple.
I would have enjoyed doing the updates,  maybe in the future. 
Regards 
Bob

Dai wrote: I coupled it with HH-grade brake pads which helped again. I'm also running cast-iron discs

I was under the impression you shouldn't use HH pads with cast discs, HH is strictly for harder stainless discs? I've gone from Ferodo Platinums to normal boring kevlar EBC on mine and it has been a big improvement though I'd still say the brakes are shockingly poor. Very squidgy also, but the smaller master cylinder means higher hydraulic pressure and therefore more braking. At least in theory..

If I didn't have the ABS to contend with I'd fit a 16v/1100 front end and call it a day. Going with the 1100 throttle bodies makes this even easier as the 1100 throttle cable will fit straight on too from your 1100 switchgear, rather than fumbling about filing things to make them fit together. As it is though I just use all the brakes on offer and have managed not to die yet, not even once..!

Snod Blatter wrote:I was under the impression you shouldn't use HH pads with cast discs, HH is strictly for harder stainless discs?

Depends how vicious you are with the brakes. Plan ahead Jack - plan ahead!