I can recommend these Vessel JIS Impacta drivers from Japan from Amazon. Not only are they proper JIS screw drivers, they have a built-in impact driver. It's so much easier to disassemble an old set of Japanese carbs with the correct tools.
OK, I'm intrigued. How does the impact function work?
You tap/bash on the end with a hammer.
Hit the end of the screwdriver with a hammer, there's a built in mechanism in the handle that gives it a counterclockwise rotation. The JIS tip sometimes even works on screws already damaged by the previous ham-fisted mechanic with a Phillips screwdriver.
Well I do enjoy hitting things with a hammer. :) Thanks for the review and info.