Allan,
I actually admire the AMAL. It was made to fit a very wide variety of bikes and with a wide range of adjustments to get the mixture right. My brother put a pair on his aircooled VW bug. I am a fan of the carbs because they work very well when you get it right. I think the bikes were probably factory jetted a bit rich to protect the engine from overheating. From a manufacturing viewpoint they are an engineers dream because of simplicity and one basic carb has many applications and interchangeable parts..

Mr Mike