Mikuni VM24

[Duccout]

I have to agree with George. You do not know what your engine is, so it could be a Sebring or Mk 3 or Scrambler, and the carb size will depend on what state of tune the engine is in and how you are going to use it. I would think that a 28mm would be a good choice for a Sebring for gentle use, a 30mm for Mk 3 or Scrambler for something a bit more go and for outright power a 32mm. A 24mm is very small for a 350.

Colin

[Mark3Cam]

I have to agree with George. You do not know what your engine is, so it could be a Sebring or Mk 3 or Scrambler, and the carb size will depend on what state of tune the engine is in and how you are going to use it. I would think that a 28mm would be a good choice for a Sebring for gentle use, a 30mm for Mk 3 or Scrambler for something a bit more go and for outright power a 32mm. A 24mm is very small for a 350.

Colin

Really appreciate all the input, shame I ordered a rebuild kit for the VM 24 already. Yeah the frame numbers lined the bike up with likely being a 68 Mark 3 but the engine numbers make it a 72 350 and I guess not much to go as to what that would have come out of. Regardless all signs point to a VM30 to save myself some grief! On the upside it will save me rebuilding a carb

[Mark3Cam]

Thanks for the advice boys - have a VM30 on the way

[LaceyDucati]

You don't say which model your 350 is, I suspect it is a narrowcase 350 if someone has fitted a VM24mm. The original carb on a 350 Sebring is a Dellorto UB24BS and the VM24 would be a suitable replacement for original if you only require original performance. The Sebring has a small inlet port and a 28 or 30mm carb will be to large without modification to the porting. The Sebring is a "cooking" model and the performance will be fine for it's needs on a 24mm carb. Carb size will depend on model, port size and desired performance and use.

Regards Nigel

[George]

Would not the full engine number give you an idea of model and year. I have some info in Ian Falloon's book of overhead camshaft singles. Can never be sure head is original but measuring diameter of inlet tract will give you maximum carb size.

[Mark3Cam]

You don't say which model your 350 is, I suspect it is a narrowcase 350 if someone has fitted a VM24mm. The original carb on a 350 Sebring is a Dellorto UB24BS and the VM24 would be a suitable replacement for original if you only require original performance. The Sebring has a small inlet port and a 28 or 30mm carb will be to large without modification to the porting. The Sebring is a "cooking" model and the performance will be fine for it's needs on a 24mm carb. Carb size will depend on model, port size and desired performance and use.

Regards Nigel

Engine was identified on here as a widecase and the gland nut suggested it was a ‘72.
Inlet is 30mm but by the time I factor wall thickness on neck of spigot on the Mikuni It measures out to a hair under 32mm so a VM30 should work….here’s some pictures of the engine for those that hadn’t seen it, along with number.

84B71E22-B618-456B-9960-5E85CC9F13BC.jpeg

28AFE839-00E2-47C7-9452-42D1C0D2DD84.jpeg

41EC4009-2BBF-4ED4-8583-BCB92F0287FC.jpeg

[Mark3Cam]

Here’s where my bike and it’s numbers fit in the list, from my first inquiries into figuring out what I had. My frame remains a mystery….
My bike is the first one listed in red
The engine model stamp was mostly ground off but was able to read a 350 in there faintly

.

55069006-A589-4F7B-8E58-65AB54A7E877.jpeg

[ducwiz]

Engine was identified on here as a widecase and the gland nut suggested it was a ‘72.

If "gland nut" denotes the feedthrough for the alternator cable, this engine should be idntified as a '73/74 model. This type of gland nut, the large brass or bronze version with a single hole-rubber grommet , was used with the Motoplat alternator/ignition systems. Ducati sytems used the same nut, but a dual-hole grommet. The cases for the earlier alternator used with the points ignition came with a nut with smaller thread, and made of black bakelite.
Refer to parts catalog:

wide_case_1974-030.jpg

wide_case_1974-028.jpg

cheers Hans

[LaceyDucati]

It wasn't obvious from the post that this was a W/C. It's obviously from these pictures it's W/C probably circa 1973 and a 24mm carb is too small relative to the port size. A strange choice of carb for the previous owner.

The port has obviously been modified in some way if it is close to 32mm. The largest standard port on a spring valve W/C single is 29mm. As you say a 30mm carb should work OK.

Regards Nigel

[Jordan]

The cases for the earlier alternator used with the points ignition came with a nut with smaller thread, and made of black bakelite.

It might be worth noting that a Motoplat CDI type alternator also can be used with the smaller type gland nut/crankcase.