Late model 2CVs should have the 18-26 version of the 26/35 carburettor fitted, but it's always worth checking that someone hasn't fitted the older 21-24 version.
Those have different choke and jet sizes, which are not interchangeable with the jets on later carburettors.
The numbers are cast into the face of the float bowls, on the alternator side.

ken

Reading all of that, would the jet Neil has posted be a improvement to the lack of enthusiasm on 2nd? Is it worth fettling with and changin the jet, or shall I live with it?
'cos if it'll improve things I'll order one and change it, simples?

As I said James mine suffers from similar hesitation to yours, possibly worse, so as soon as the larger 107 is fitted I'll post the result. Should be tomorrow. And if it makes no difference I'll have saved you 7 quid

Cheers Ken

Will have a look later when er indoors gets home from work.. Got a price back from Boyer just need to work out how to do all this now!!!

Sorry I was trying to work out what was applicable to me,
If you could post results that'd be cool

New 107 jet fitted tonight and will road test tomorrow.

Look forward to results
If an improvement I'll get one

I suppose this is along the same line, but is the throttle pump diaphragm prone to failure? That could cause some pretty nasty hesitation too, right? :S

Look forward to hearing about the results of the road test

Well mixed blessings. Definitely smoother accelerating on the first choke. But the hesitation's still there at constant throttle between 30 and 40 in top. And sudden hard throttle after throttle closed, like in slowing down for a junction then gunning it away again, sometimes gives a big flat spot and a lurch.

Out of interest I completely stripped the carb again and blew in every orifice with compressed air and carb cleaner. But I only did this a couple of weeks ago when I fitted the overhaul kit so nothing really should have changed. Carb flange is perfectly true and I again checked the fibre/plastic carb heat insulator for hairline cracks and nothing's apparent. Throttle spindle seems a good fit wihout obvious wear and the accelerator pump is working fine.

I think as I've now got a spare 102 jet doing nothing I may just bore it out by 10% and try it. I think it could get a bit expensive continuing the trial and error jets at 7 quid each.

So nothing to lose eh?