Funnily enough, I have Mikunis, Keihins, Amal MK11s and Amal Premiers, fitted to my ‘stable’ so am able to compare them all easily.
The biggest challenge Japanese carbs give people using them on bikes they were never intended for is setting them up. Many folk struggle with Amal’s and Japanese carbs are many times more difficult to get right than Amal’s. Luckily for us, there are specialist suppliers out there and a whole internet community of people who have already done it, so buying a kit with good base settings is easy, and fine tuning with the help of the community isn’t so difficult any more. The really serious can do what Ken did and fit a gas analyser to their bike, but not many folk do this.
An issue I’ve had with Mikunis and Keihin carbs is their sensitivity to dirt. I’ve had them flooding out of the overflow pipe and, long story short, it’s been down to dirt particles so small I could hardly see them. Perhaps it’s not a ‘fault’ as such, it’s actually a symptom of the greater precision of the Japanese instruments and more of a calibration issue of the owners more used to Amal’s, which will run happily in situations where the Japanese instruments will not. Fitting good filters cures it of course.
Actually, the Amal’s work very well indeed, they start well, run well, tick over well, etc.
The MK11s were jetted incorrectly from Amal, not by error as such, but due to the fact that the Triumph manual and therefore the Amal, upon which they are based, are both wrong!
The Premiers came with pilot jets that turned out to be too small, this was a common issue which I believe Amal have now rectified.
Neither pair of Amal’s came with any swarf or assembly errors, but due to the reports of this, I did strip and inspect carefully.
So, overall, I’m happy with them all. The Japanese carbs are fitted to rather special / tuned engines, the Keihins have accelerator pumps which work very well, and, although I’ve never tried Amals in these applications, I cannot imagine them matching the performance of the Japanese carbs. And anyway, new Amal’s are not available in these sizes. The Amal’s I have are fitted to fairly standard bikes, and as they work so well, I see zero advantage in swapping these for Japanese instruments.
So once again it’s bad news for those looking for a fight cos IMHO it’s all down to different horses for different courses and personal preference.