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I think a Kanguro M/C has the smaller piston, certainly works well on my single disc, non-original (but still cherished) Strada. I seem to recall a discussion where a conclusion was that a 19 mm M/C was more suited to a twin disc set up than single disc. As for spares for Chinese copies, Ariete would most likely fit, though a complete new unit would probably be cheaper, too.

After reading a thread in the Tre e mezzo section of this forum I thought that I would see if fitting the Honda CBF125 master cylinder would improve the feel of the front brake on my 500 (currently very wooden). I ended up buying two from breakers because I thought that the first was possibly leaking within the piston/cylinder bore but the second was the same. At the same time I bought a mastercylinder seal kit. I have concluded though that the problem with the use of these 12.7mm diameter piston mastercylinders is that there is not sufficient stroke to move the two calipers without the handlebar lever coming almost to the bar. That said, action was certainly very light with lots of feel and I am sure that this mastercylinder would be an excellent alternative to the standard offering, on a single disc set up.

Therefore I have the following for sale:
2 off Nissin mastercylinders both in good condition), only one has the lever (gravel rash on the end ball) + mastercylinder seal kit (brand new)
All these could be yours for £40 + p&p ono.
See For Sale section of this forum.

Thanks,
Charles

This site has been very handy to me over the years. You can find the ideal master cylinder bore size to suit the calipers you are using.

https://web.archive.org/web/20070922085 ... linder.htm

I believe he is retiring, so it may be worth taking a screenshot of the chart if it's of any value to you.

Cheers,

Kamel.

Hi Kamel,

Thanks for the link but I am not sure that I agree with his recommendations about the optimal ratio but I will give it closer scrutiny to make sure i am misinterpreting the chart.
I have a twin disc set up and a 16mm m/cyl piston with calipers fitted with 38mm pistons (I think) so according to the chart that gives me a ratio of 11.28 which is a long way off the recommended ratio of 27.1, Even with the 1/2" mastercylinder from the Honda CBF125 that would only result in a ratio of 17.91 still on the commentators idea of wooden, it was in fact far from wooden in feel - felt good but I was concerned about the amount of movement of the lever, almost back to the handle bar.
Personally I would like to find a m/cylinder of c.14mm but they seem far and few between - I think Brembo used to make one (could have been 15?) but no longer but will keep looking.

Perhaps I have totally misunderstood the www.vintagebrake article?

Adios,
Charles

Seagreen wrote: ↑12 Apr 2021 19:59 I have a twin disc set up and a 16mm m/cyl piston with calipers fitted with 38mm pistons (I think) so according to the chart that gives me a ratio of 11.28 which is a long way off the recommended ratio of 27.1

With twin disks (and calipers) you have four pistons of 38 mm diameter, so with a 16 mm master cylinder, you have a 22.56:1 ratio according to the chart.

AntietamClassicCycle wrote: ↑13 Apr 2021 14:00

Seagreen wrote: ↑12 Apr 2021 19:59 I have a twin disc set up and a 16mm m/cyl piston with calipers fitted with 38mm pistons (I think) so according to the chart that gives me a ratio of 11.28 which is a long way off the recommended ratio of 27.1

With twin disks (and calipers) you have four pistons of 38 mm diameter, so with a 16 mm master cylinder, you have a 22.56:1 ratio according to the chart.

Hi Antietem, thanks for helping me out on that piston number - I should have noticed that ( ) = Number of ACTIVE pistons !!! Makes much more sense now so all I need to do is find a mastercylinder of 14-15mm diameter piston size - anyone know of one? This is a classic example of how good forums can be. Thnaks again,
Adios,
Charles

Be a little cautious with the diameters claimed by manufacturers.
Master cylinders are often actually a very different diameter to the claimed size. Also (a lesser importance) the real effective diameter of a piston is different depending on whether the pressure seal is mounted on the piston, or mounted on the cylinder e.g. if the seal is mounted on the piston then the effective diameter is that of the cylinder. If the seal is mounted on the bore then the effective diameter is that of the piston. The same holds true for the pistons in the caliper.
G&A

HI Bumblebee,

Thanks for the advice, I had not appreciated that subtlety.

Adios,
Charles

Hi
Quick related Q- is there anywhere to buy ready made braided hozes for a twin disc front brake set up? The P. O. fitted one to the rear, but not the front, surprisingly

Try the usual suspects...

Goodridge
Hel
Venhill

I sent my hoses off to Venhill and they made some for me. In my opinion the black is better than the silvery colour of bare metal.

Hel have the following but not sure if for single or twin discs.

https://www.helperformance.com/moto-mor ... rake-lines

I have HEL twin front brake lines, I do not have a splitter but run the full length from the m/c to each caliper. At the time someone made them up whilst I waited
which was pretty exemplary but not sure if that is still possible. Totally seamless in operation. They are only a spit away hence my choice.
I have a narrower diameter m/c for the only reason that mine failed in Bedfordshire, which is a fair distance to ride on a back brake, and I was lucky to acquire one. If I say the original is 19mm and the replacement is 16mm, ( cannot be certain) the brake action is light but maybe if anything too powerful. I’ll take that over crappy swinging ATE brakes any day.
John

ATE brakes are not a good example!

I fitted black HEL recently.
I seem to remember the Morini kit they sell lists 3 lines for the front which confused me as I currently have two 350K1’s and like John’s there is no splitter on either bike.
I just measured the existing, noting there was a 20 degree kink in the banjo fitting on one end of each hose (if I remember correctly) and ordered them without mentioning what bike they were for.
They came as ordered and fitted fine.

Many than
ks for your help. An HEL kit is looking likely

Have discovered the master cylinder is leaking-both seals around the plunger apper to have failed. Any pointers where I can get replacents quickly? The plunger appears to be 19mm dia. Thanks