C15 - replacement carburettor?

[Dean Southall]

Allen's Performance do  Mikuni kit direct replacement for C15 carb
https://www.allensperformance.co.uk/carb-kit/carb-kit-listings/

[cdsdorset]

If you buy a wassel it will probably come  set up for a different bike and you may need to reset. Don't forget about cable differences.

[AdrianS]

I've got a Wassell concentric on my D14 Bantam. Works fine.
Try also Hitchcock for a monobloc. They have good stock and will jet accordingly. I bought one for my B40, bolted it on and there was an instant improvement ( not as much as having the lollipop distributor rebuilt though).

[B44R Victor]

I bought a brand new carb for my B44 from Amal direct and it's beautifully engineered.  Amal are in Spitfire House, Castle Road, Salisbury, Wiltshire SP1 3SB (Tel 01722 334221).  The Amal part number is the same as the original 1967 carb but has Amal's own seat modification for lead free petrol.  The other thing I was pleased with was the first class service I received from them and their expert advice at the other end of the phone.  A rare thing these days!

Buy British and go to Amal.

[chaz]

that said, I bought an Amal from Salisbury and had to go back to India (its where they are cast and machined now) as when Salisbury tried to build it they couldnt, incorrectly bored, took extra month to get.

[Barnsey]

I bought a concentric carb to fit to my C15 only to find it wouldn't fit with the original air/battery box.

[neil1964]

Just to throw other thoughts into the equation (on the same basis as the £35 battery vs  the £65).  I have had lots of fun (not!) over the years sorting out carburrettors on lod machines (I amigain like many here).  I make some points about Amals (as I tend to stick with those on bikes) but have SUs and Webers on my 4 wheeled vehicles (both have good and bad points.
What I have discovered and hope you find it helpful:
Old original Amal concentrics are made of Mazak (aka Zamak) and because the throttle slides were originally of very similar material they wore badly and if you were not careful when fitting them to the inlet manifold they also often distorted the flange leading to air leaks and sticking slides.  For this reason you should be careful buying second hand concentrics. 
Monoblocks fared better and the ones I have had were brass slides (which also wear) so if you have a good one (however it sounds like you do not) I would work with that.
At present I have a modified (for 4-stroke) 1038 concentric on my ABSAF 600 GS using solid brass slide, adjustable stay up float, aluminium Viton tipped needle and nylon coated throttle cable.  The flange is straight and body not worn, jetting is correct.  It is hard to imagine a carburettor that works any better.
Float needle:

Adjustable float (see the brass tang for fuel level adjustment):

On my ZB34GS I also have a pretty new 930 concentric with a new Amal coated slide and the same adjustable float and aluminium float needle and Viton tip.
Pic of the coated slides:
Newer Amal concentrics are made of cast aluminium (not Mazak) have coated slides as standard, the light weight Viton tipped float needles.
All these things add up to a carburettor that works well on an old motorcycle (there is loads of info on settings - as mentioned if you go to Surrey Cycles or similar and tell them what it is for, whether you have an air filter, different compression etc (all things that affect the settings) they will supply you with the correct instrument.
The Wassell carbs are just like the original Concentrics (AFAIK) and will almost certainly develop the same problems, given time and use and personally I would go with a concentric carb (Amal or Wassell) with the goodies I have pics of.
My next task is to get the ZB running properly with its correct 10TT9 once I have rebuilt it.
Remember to use petrol pipes suitable for Ethanol petrol and ideally if the bike is standing to any time empty your carb and petroltank as it will rot the inside of your tank and fur up your pilot jet making starting and low speed running almost impossible when you come to use it again (scan the fora for people having these issues.............)