The one that 50 years of working with engines helps me to know will be suitable?

it's called a reamer, which works a bit more precise than a drill.
Jets could wear out with use, they get wider because of erosion, or get narrower because of gum build up or corrosion.

I get the hidden message, for me to know and you to wonder about

In that case, here's your starter for ten...

A jet which is nominally a '110' according to Solex, Mikuni and probably others, has a bore which is exceedingly close to 1.1mm.

ken

Hi Ken - didn't mean to be vague on the ignition setting - it's around 34 degrees on dynamic.
How could I tell if it was running lean and getting hot, if not pinking?

[quote="Nelsthebass"

......How could I tell if it was running lean and getting hot, if not pinking?[/quote]

You could do worse than try one of these:

http://www.carbtune.co.uk/colortune.html

I've used it on bikes and had excellent results. Not sure if it will fit 2cv plug threads though.

Nels,
that flat spot which you mentioned is characteristic of a carburettor which is still fitted with the original jets.
Those jets were fine with leaded fuel, but the additives in unleaded contain 'used' oxygen, which has the effect of weakening the mixture.
Two 'steps' up in jet size will correct the mixture for current fuels and since each 'step' is 2.5, that means the original 102.5 needs to be increased to 107.5.
That may not seem like much, however since the flow capacity of a jet is directly proportional to the square of its diameter, that's a 10% increase in flow.
Once the change is made, the motor usually feels as though there's more torque lower down the rev range, so less need to trash it and mpg can often improve...

@ Chris,
those devices may be useful for setting the _idle_ mixture on multi-carburettored engines, but no use for checking the mixture under full load/wide open throttle use.

ken

Cheers Ken - I will have a look at what I've got in the selection of carbs I have and also some jets I've changed over the years - I suspect that I have the original jet from the Beige Beast which will be larger than standard 2CV ones.?....Paul

120 or 125?
Too, too much...

Somehow I suspected that! The car is running now with 9:1 pistons though so is only the forced induction the reason why they had such large main jets?