I have an 1984 V35ll that I found in a barn and renovated I have a problem with the brakes I know the footbrake operates the rear brake and the lefthand front brake and they are fine with plenty of stopping power, my problem is the right hand front has very little stopping power, both pistons are free and the front brake lever feels fine (no air in the system) but the braking effect of this one dual piston calliper is really weak any one had the same problem and if you have how did you cure it.
Does that have a cable running from the lever to a remote master cylinder a la V50 II ?
No the lever pushes the piston in the master cylinder and there appears to be plenty of pressure there that I would expect a decent enough brake but I feel I would be better off if I dragged my feet.
I am starting to think along the lines of the master cylinder seals being swollen and causing a problem.
if its the original system with a remote master cylinder under the fuel tank they are in a word crap… The stretch in the bowden cable and small master cylinder make them very spongy and give little more than gentle deceleration!
Totally rebuilt my v35’s one with no improvment
What about this Campagnolo style improvement…?
that may do the trick unless you want to splash out on a handle bar mounted master cylinder!
The way I read it the master cylinder is all up on the bars – operating direct from the lever.
Generally in operation if you have problems you would expect one of two issues. Either that the lever feels very hard and wooden, with very little movement; which would suggest seized pistons, too hard pad material or possible even wrong rotor material (stainless rather than cast iron). Conversely you can have a soft lever where it will pull well back but to no great effect. That might be air in the system, or possibly older brake pipes with some swelling, or even where the pad material is starting to lift from its backing.
Beyond any of that you could try softer compound pads.
How much time have you allowed for the pads to bed in and the caliper pistons to self adjust?
If it helps at all, my Tonti front P8 + LM drilled disc is not wildy powerful either, mostly good for just scrubbing speed off. Bear in mind these brakes were designed in the 1970’s, so are what was ‘good’ then. If I need more welly generally bang on the lot. (I.e. ‘do it properly’, all the front + rear.) Also what CB said about pad compound, I would advocate Ferodo or EBC, OEM Brembo pads are generally feeble.
V50mk 2 has a remote master cylinder with a steel bowden cable running to the lever on the bars. The V50 Mk3 moved to the conventional style handle bar mounted master cylinder . Many v50-1/II have had the conventional system retro fitted
That would probably be more effective than the front brake I have at the moment 
I have 4kms on the pads and its the same now as it was then , I know both pistons are free and the pads are free in the calliper so it has to be a problem with the rubber pipes and or the master cylinder wants rebuilding.
Well I have just received a rebuild kit from Gutsibits so I will try that first.
I should add it stood for twenty years before it was rescued.