Pre-Monoblock Carburetor

[yellow B31]

If your not bothered about originality and appearance an Indian VM24 carburettor as fitted to the basic 350 Indian Enfield works a treat without any jet changes. I have one fitted to my 1949 B31. £45 off Ebay.

[scifi]

Hi Yellow B31...  Is the VM24 a 24 mm carb, i.e. less than 1 inch..?   Hitchcocks list a VM28 (out of stock.) for their Enfields , which may be the size for the B33 500cc machine.   A 26mm carb might be what is required however.

[yellow B31]

Hi The VM24 is a flange mounted carb of 24mm choke so yes just under an inch. The VM28 is a stub mounting so would require a flange adaptor to fit. £53 on Ebay

[Dean Southall]

Allens Performanec lis a Mikuni kit for the B33
https://www.allensperformance.co.uk/carb-kit/carb-kit-listings/

[Geoff Leake]

Morning guys, apologies for the delay in responding but thanks for your suggestions rhyatt and Stubaker58.

I'll try the people in Salisbury, it'll be interesting to see what they say and at the very least it's another useful contact. However, since my last post, I've spoken to a pal who's suggested (as you have Stubaker) that the monobloc is the way to go as it's more in keeping. So I'm sure we'll get there in the end.

Thanks again to everyone for their very helpful contributions. What a great forum this is!

[Geoff Leake]

Hi Yellow b31, will the Indian VM 24 carb you referred to on your B31 do the same job on the B33?

[yellow B31]

It will certainly run ok on part throttle but if you want to ride flat out every where it will no doubt be lacking. The B33 carb is 1 1/16 (27mm) choke so using the VM24 your 3mm smaller but in numbers I can visualise 1/8 inch smaller on diameter (1/16 per side). If I had a B33 I would consider it worth a try at £45.
Have used these cheapo carbs on a Norton single and a 350 Russian 2 stroke with good results. I run my B31 at 50mph and responds well to the throttle, cannot fault the VM24.

[Stubaker58]

It's worth remembering that although 3mm difference doesn't sound much it works out as a 25% increase in area.

[yellow B31]

Do you think you would notice the difference in general riding? Whenever I see old Brit singles on the road and I include myself in this category no one is rushing about.

[Stubaker58]

That's very true!😁

[idie]

That is all very well using a smaller carb until the day comes when you need a bit more get up and go in an emergency.The manufacturer  knew what they were doing when they specified a carb of a certain size.

[yellow B31]

Yes your quite right idie the correct carb is the way to go, just offering an option as £480 for a new 276 would hurt my pocket.

[DAVE BRADY]

Hi,

I suppose it comes down to what you are going to do with this bike.  A 'restoration' to original will require the original type carb. especially for showing.  For regular use and with an eye to something a bit more in keeping the monobloc could be the next choice. If all you want is a some reliable practicality then a concentric could be the best choice.  Clean up the original carb and keep it as an ornament and have a picture on your phone to show any critics that you have it.  In the mean time search a few jumbles for the bits you need for the original.

Dave.

[Geoff Leake]

Morning guys, Thanks again for all of the very useful observations and informed suggestions, I now have plenty to go on. Since I'm reluctant to spend a fortune on a new carb, I'm probably in for several hours scoring the autojumbles. Unless anybody out there has a good useable body of the original type - mine's reusable (it's the slide that's defective) but has lost it's coating and looks lousy! Thanks again everybody.