JIS Screwdrivers: What They Are, and Why You Need a Set

By Cameron Vanderhorst - November 13, 2019

Possibly the best-kept secret in the tool world, you need a set of these in your box if you have an older Harley.

If you’ve got an older Harley-Davidson at home, then chances are you work on it yourself. There’s also a good chance that it’s carbureted. If both of those situations apply to you, then read on – this may change the way you work on your bike!

Harley-Davidson may be the ultimate American motorcycle, but the carburetor on your bike is very likely Japanese. That’s not a bad thing – the Japanese are actually really good at building carburetors.

However, if you’ve ever tried to take apart your carburetor for cleaning or adjustment, there’s a good chance that you stripped one or more of the screws holding it together. Many folks think that happens because the metal that the screws are made out of is too soft, but it’s more complicated than that.

It sounds like a trick question – “When is a Phillips screw not a Phillips screw?” The answer is that the screw’s familiar cross-shaped head is actually designed for a slightly different type of screwdriver, the JIS. JIS stands for “Japanese Industrial Standard,” and it’s different from a Phillips head in one very important way.

Phillips screwdrivers are designed to “cam out” – that is, rotate out of the head of the fastener – when too much torque is applied. By contrast, JIS screwdrivers will continue applying torque. What this means for DIYers like us is that, when we use the wrong screwdriver – a Phillips screwdriver on a JIS screw – the head of the screw gets rounded when the tool cams out.

One website, RevLimiter.net, published an in-depth article about the numerous seemingly minor differences between JIS screwdrivers and a Phillips screwdrivers. The article also offers a good tip: if you’re in a bind, you can flatten the head on an old Phillips screwdriver and use it to get the job done.

Obviously, that’s less than ideal, and we always recommend using the right tool for the job whenever possible. Unfortunately, most hardware stores don’t carry JIS screwdrivers in stock. Despite the sheer volume of Japanese cars, trucks, and motorcycles on the road, most people still use Phillips screwdrivers when working on them, and most stores don’t think to stock the necessary tools.

However, good-quality JIS screwdrivers and bit sets are easily available online, and often at prices that won’t break the bank. If your Harley has a carburetor, or you work on your friend’s metric bikes often, we recommend picking up a set.

Photos: RevLimiter.net; Harley-Davidson