MB v UB Dellorto

[Paddy]

What is the difference between MB and UB Dellorto carbs ? I seem toi remember MB's were used on 2 strokes but i cant see why that should really make a difference ?
TIA

Paddy

[Harvey]

The Dellorto for a two stroke has a shroud around the front of the needle jet.

[Paddy]

Is it fixed or an addition ?

[Harvey]

You can push it out and fit the flush type, that the 4 stroke use.
I had a 41mm 2 stroke version on a 360 Bulltaco, and changed the brass piece with the shroud to the flush one, to fit to a 450 desmo.

[Paddy]

OK cheers for that, i wonder if that is the only difference then between an MB and a UB.... Seems odd to change the designation on the body because of a removable addition ?

[Harvey]

The accelerator pump was blanked off, had a choke, may have been others that I don't remember, but that was all I did to have it run well on the 450.

[Paddy]

I think we are talking cross purposes here
The dellorto 1960's UB24 i have has no accelerator pump, neither does the MB24 i have , they are prehistoric Most 450s were running VHB or PHF in the 1970s ?

[Eldert]

the only Ducati with a PHF was the 239 sold in France

Eldert

[Paddy]

Yes i had a 239 for a while with a PHF30, a lot of them ended up over here as they didnt sell well in France., you would surprised how many 350 and 450 are running about with PHF 36s on

[jbcollier]

Not an expert but I thought the MA/MB carbs came first and the UA/UB carbs were the next development.

As to 2T vs 4T, it is not just a matter of atomizers and shrouds, the atomizer air bleed is different as well.