Which Carburetor ?

[Piers]

Hello All,

I am trying to find the right Carburetor for my 1960 24DB Roadster fitted with a 32A motor. I have searched the archive on this brilliant Forum but am still a little unclear which exact version of the S25 I should have ?

The original Carburetor had a rod operated Choke (or is it called a strangler ?) that was pushed down to operate it and twisted to release, so is it a S25/2 ? or a S25/6 ? Maybe it could be a S25/6 or S25/7 both of which have rod operated Chokes and used on Road Bikes ?

Is there a correct version ? or was any S25 Carburetor fitted during production ? I have a copy of the V.E.C 545 Parts book and while it is very good, it doesn't list the applications for each variant of S25 Carburetor so I'm struggling a bit.

Any help gratefully received.


Cheers

Piers

[John Wakefield]

The 24DB has the 32A (road) engine which as standard (source 'Villiers Singles & Twins' by Bacon) was fitted with a S25/2 rod operated choke slide. So the 32A in the 24DB would have had the rod operated system. You may prefer to fit the cable operated choke as this gives better control of the choke. It was mainly micro cars like the Bond that had the cable operated choke (for obvious reasons) together with an idle adjustment screw that would be the S25/7 and /8 Again its an advantage to fit a carb with idle screw on a bike, I have one on my 25DC Mk2 East Coaster. The cable choke system can be fitted in place of the rod system by fitting the relative parts.

[garybam4711]

I have a s25 fitted to my single S25/5 as it has a idle adjustment
gary

[John Wakefield]

The S25/5 is listed as Bored out to 1" choke, no choke slide, 32A engines. No mention of idle screw, so looks as though the one you have Garry has been modified, easy job to drill and tap the carb body and fit an idle screw. The casting already has the depression for the drilling. Also needs a slight chamfer on throttle slide where the idle screw locates on it.

[Piers]

Hello John & Gary,

Thank you ever so much for the really useful replies.

It makes perfect sense to choose a Carburetor that has a cable controlled Choke and throttle stop, so I guess I be looking out for a S25/3 or S25/8. There is always the alternative of obtaining one of the other S25 variants and converting it to suit.

Is there any advantage of fitting a S25 with the 1" bore on a road bike ? were these carburetor use for racing ? I'm not really searching for speed from my 24DB, I just want it to be reliable, bomb proof and reasonable original looking.

Thanks again for all you guy's help.

Cheers

Piers

[John Wakefield]

Hello John & Gary,



Is there any advantage of fitting a S25 with the 1" bore on a road bike ? were these carburetor use for racing ? I'm not really searching for speed from my 24DB, I just want it to be reliable, bomb proof and reasonable original looking.

Thanks again for all you guy's help.

Cheers

Piers

No non at all, the bore is only 0.4mm (0.016 inch) larger and as such makes no difference.