[geichal]

Ouch Giechal, 40 is kind of low but if you're having fun...who cares! I blame the 34mm carb.  When i was experimenting with a 34mm roundslide mikuni I was getting about 45mpg with a fairly stock engine setup (not stock exhaust).
 
With the 1 3/16" (about 30mm) monobloc and the stack i avg 50-55mpg with spirited driving. This is with my current hopped up setup. I could probably touch 60mpg but I've never managed to drive that way for an entire tank haha. When i fit ace's mondello head and magnum cams for dyno testing I will be switching over to a mikuni tm32.
I didnt notice much loss in mileage with the addition of the stack on the amal, maybe just a hair of difference if that. I think the stack actually gave me a more efficient combustion since I would have expected to lose a lot more mileage considering I did have to go larger on the main jet by a ridiculously large margin. The improvement in power across the rev band was huge. 

I had bought the carb cheap on ebay very early in my project on advice from a guy who was a flat track racer. I got the stack for free.  If I had it to do over, I wouldn't have gone so big.  When I get my bottom done  , I may get one of Aces' more aggressive cams and really get freaky with it! (Now I'm running a cam out of a "62" Redditch Bullet).  I have a buddy with a very sexy Amal GP that I'm trying to weasel out of him. That would be super sexy with a stack!
geichal

[chumma7]

Amal GP's are a seriously beautiful piece. Just curious.. what bike is he running it on? Has he managed to get any idle out of it? I know they were strictly designed for all out racing and don't have any idling circuit.
Despite the loss in mileage the 34mm carb does perform very well on our bikes, specially past mid throttle. I think a 32mm is the perfect size with our ports but the 34mm surprised me.

[geichal]

Amal GP's are a seriously beautiful piece. Just curious.. what bike is he running it on? Has he managed to get any idle out of it? I know they were strictly designed for all out racing and don't have any idling circuit.
Despite the loss in mileage the 34mm carb does perform very well on our bikes, specially past mid throttle. I think a 32mm is the perfect size with our ports but the 34mm surprised me.
BSA DBD34 (I think), I've never actually seen the bike run.  I believe it (the carb) was ordered new from AMAL a couple of years ago for a vintage track racer, but that project hasn't been completed. 
I agree about the 34mm, with the exception of poor fuel economy, it kicks ass.  I blended the ports on my head to match the carb.  Plus the head has been flowed and large kibblewhite valves installed.  My setup seems to work very well with the Redditch cams.  I tried it with the stock cams and that was disappointing!  I believe Aces's clubman cams are similar to the Redditch cams.

geichal

[ace.cafe]

BSA DBD34 (I think), I've never actually seen the bike run.  I believe it (the carb) was ordered new from AMAL a couple of years ago for a vintage track racer, but that project hasn't been completed.  
I agree about the 34mm, with the exception of poor fuel economy, it kicks ass.  I blended the ports on my head to match the carb.  Plus the head has been flowed and large kibblewhite valves installed.  My setup seems to work very well with the Redditch cams.  I tried it with the stock cams and that was disappointing!  I believe Aces's clubman cams are similar to the Redditch cams.

geichal

I wouldn't pick a  GP carb for street use.
It might be good for vintage racing, or look good on a bike in a museum, but it's not the best choice for a street machine.
A Mikuni flat-slide carb is a much better performing all-around carb.

The Clubman Cams are somewhat similar to the Redditch cam timing, with a bit of difference, most notably the5-degree later intake closing timing of the Clubman Cam timing, and the later exhaust opening timing too.
The Redditch cams are nice, though, and give suitably more spirited results when paired with a good-flowing intake system..