Apparently... "Japanese Industrial Standard (JIS) screwdrivers are designed and manufactured for the perfect fit that will prevent camouts the slipping that strips the heads of Phillips screws."
Don't seem to rare to me but here's another link to some: http://www.rjrcooltools.com/vessel.cfm
If you ever stripped out the screws removing them on a japanese carb you know what I mean. My search for good JIS screwdrivers revealed the same lower quality screwdrivers sold by RC/hobby or electronic repair venders. PB Swiss apparently is one of the highest quality tool makers out there and their prices were not much higher.
Anyone who has worked on vintage Japanese motorcycles knows all about those JIS screws. The Phillips screwdrivers sold in this country do not fit the screwheads. The result, especially with case screws, is usually a "camout" or what we would call a stripped head. Then it's time to reach for the drill. An impact driver usually works if the head is still in good condition, but they frequently damage the head too. Most of us replace the screws with stainless allens when we get them out, but if you're building a show bike that's not acceptable of course. Everything has to be original, including the case screws.
Huh. Well, I'm 48 years old and started riding dirtbikes when I was 6. So I've worked on my fair share of vintage Japanese motorcycles and stripped out my fair share of float bowl screws (and got good with the hand-held impact driver), but I was under the impression it was more the soft metals than the screwdriver heads.
I believe I have these in my current sets, but don't have any vintage Japanese stuff around to test that theory.
JIS screws are 58 degrees and have a blunt point, while the Phillips screws have an angle of 55 degrees and are more pointed at the tip.
One modification that can be made to a Phillips screwdriver is to grind off the tip of the blade thereby shortening the taper.
I’m not sure if it’s he same thing (bet it is - without the identifier) but I had the same issue with British carb screws in the 70’s. GM started using POZIDRIVE screws and noticed they had an identifier mark which was a small line between the screwdriver slots of the phillips, also a more blunt end and/or different angle.. It was the same thing the British were using for years. Those screws would always be messed up by using a regular phillips.. The POZIDRIVE fixed that.