There is no denying the Round Slide VM series Mikuni is far more refined and superior in every way to the Amal, save for weight and subjectively possible, asthetics.
I've heard often how once these track and street proven world class carbs all of the sudden manifest float problems as soon as they sense they've been installed on a Brit bike...... but I've had no more float problems with Mikuni's than Amals, regardless of the application. but then again.... I don't mount them hanging off the end of a 6 inch bit rubber hose to bounce around like a bobble head..... and typically brace them up regardless of the runner length. And don't let yourself forget how many checkered flags that bike's fitted with VM's have taken in GP, drags, and most any other kinds of racing worldwide, one can think of.....
The Amal has HUGE comparative jumps between selective tuning parts like slides, needle jets, and needles...... and lacks things like a selective air bleed, an actual emulsion tube, hard chrome slides at no additional cost, etc that other much more refined metering devices have.
This does however, make them less fuss to make them do what they will do, however compromised that is for one's application. Let's face it, how often do you hear about a guy tuning a Triumph using both a dyno and four gas analyzer?
Many people who don't like Mikunis after trying them, simply lack the patience or understanding to dial them in to their engine. They aren't nearly as "one needle jet and one needle and one slide cutaway" fits all kinda carb as the Amal is.... I suppose just as many don't like them because they think they are ugly or out of place on a certain kind of bike.
Plenty of much more refined and precise metering devices do exist and many are to be had for nearly nothing. A prime example of a very suitable carb for a Triumph twin would be say the units off a 250 Ninja, perfect size and they work very well. Many of the 28-34mm modern flatslides, both with CV and mechanical slides will work quite well too but there are many other possibilities.
Now the Amal becomes very inadequate when put on a highly modified engine that the builder really wants to dial in and make quite crisp.
Of course the Amal can be made to work on most anything. I have a Mark 1.5 928 (these are rare and I'd like more of them in any size) on my HD flatty. It's been higly modified internally and works flawlessly, facing forward with an open velocity stack. Some of you may have seen it on the cover of Iron Works Dec 2004.
Doing a 4 valve big twin with multiple runners and valves..... and this one will have it's mixing chores handles with an EFI unit from Accel DFI.
So by all means..... give something else a shot and unless you dig something up off a 20's tractor and aren't confident with your small drills..... it shouldn't be hard at all to find something that will offer both better performance and fuel mileage than the Amal.
FWIW...... my Triumph twins normally break better than 60mpg with modified Amals...... pretty simple to put a modern carb on them and break 70mpg unless you stick with the nearly useless stock gearing as well.
