Motoscrubs.com

I’m almost afraid to ask for fear of inciting argument, but what are the latest recommendations for alternative carbs for a 450 (desmo or otherwise). I’m really not keen on throwing on a knackered old VHB Dellorto.

Thanks in advance.

Ian

Hi Ian,

I think that the answer depends on how you are going to use the bike and the state of tune. A bigger carb needs a bigger inlet tract and inlet valve and higher revs to produce more power, which means that it will be a pain to use at lower speeds. My guess is that most will recommend a 32mm for best all-round road performance.

Colin

Thanks Colin, my racing days are long gone (not that they ever existed except in my mind) so ‘pottering around’ is probably ly a fair description of intended use.

I’m presuming some variety of Dellorto, Amal or Mikuni will work but which one?

Ian

Hello Ian
I have 2 standard 450s with PHF32 carbs
They work well enough for road riding.
Start with the standard Darmah jetting , that will get you very close.
(also I disconnected the pump arm from the lid so no pump)
You may have to chase a manifold to suit.
Others use Mikuni with success (see Dan’s posts)
Graeme

Hi Ian

If you want to stay 'period correct':
Mototrans put a Dell'Orto PHF32 on the Vento (altho' that's a 350 not a 450, to be sure). Seems to work well enuf.
And the 239cc French-market Mark3/Desmo also used a PHF - 30 this time.

Otherwise if you want to get all modern, Mikuni seems the preferred choice. Can't help with what model or nuttin', tho'.

(P.s Bruno Spaggieri used a PHM40 on his 450 racer. But that's probably not a road you want to go down ... )

Aye Ian,

Lot of reading! Previous threads on this site.

450_Desmo_carb 24 pages!

AMAL_2932_carb_E10_450_MKIII_settings

These are the settings that I am currently running and getting a nice light tan ring around the top of the plug insulator and over the earth electrode. General running on 'A' roads through to 'Unclassified' roads so top whack 70mph, mostly in the 40mph to 60mph range and using Miller's Oils 'VSPe Power Plus' fuel treatment, I am averaging 80mpg.

However, there may be a fly in the ointment as AMAL are only building carbs to order and I had heard that they didn't have any 2932 bodies in stock. THAT IS HERESAY, so speak with AMAL directly, if you should choose to use one of their carbs.

Good health, Bill

Ventodue wrote:
(P.s Bruno Spaggieri used a PHM40 on his 450 racer. But that's probably not a road you want to go down ... )

I was thinking I might grab one of the PHM40s off my '82 Darmah just as an an experiment but to be honest I think the Darmah is over-carbed - earlier Darmahs had 32s and are much more civilised on the street.

themoudie wrote:Aye Ian,

Lot of reading! Previous threads on this site.

Thanks Bill, that's a useful steer.

Ian

Pleasure Ian.

Bill

IanHood wrote: .. but to be honest I think the Darmah is over-carbed - earlier Darmahs had 32s and are much more civilised on the street.

IME, 40 PHMs do nothing for a standard Dramah (be it fitted with Contis or not). You need to fit the full "Tuning Kit" of cams and bigger valves to see any 'benefit'.

(Better off fitting 36s. But scarcely worth the trouble, even so ...)