What is a JIS Screwdriver?
Article by Mark Trotta
Many people think that all cross-head fasteners are Phillips head, but there are two distinctive styles.
What Are JIS Screws?
JIS stands for "Japanese Industrial Standard", which are fasteners found on Japanese products and vehicles.
Similar to a Phillips head screw, JIS fasteners have a "+" shaped recess on the head, but require a JIS screwdriver to remove and install them properly.
No Cam-Out
Whereas Phillips screwdrivers are designed to "cam out" (slip or pop out) to prevent over-tightening, a JIS driver sits tight into the screw recess. This allows you to tighten without fear of stripping and popping out.
In addition to cars and motorcycles, such as Honda, Yamaha, Suzuki, Kawasaki, and Toyota, they are also found on snowmobiles, ATV, UTV, 3-Wheelers, PWC'S and other products made in Japan.
Occasionally, I do repair work on classic Japanese motorcycles, such as this 1977 Kawasaki KZ650. And when I do, my set of JIS screwdrivers come out.
Phillips vs JIS Screwdriver
In the picture below, notice how the the Phillips (on the left) is pointy, and the JIS driver (on the right) is flat.
Both of them will fit a cross-head screw, but only one of them will fit right.
I've heard techs complaining about cross-head fasteners rounding off, or saying that the material is too soft. In reality, they're probably trying to remove a JIS fastener with a Phillips head screwdriver.
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How Can I Tell a JIS Screw?
Most, but not all, will have a dot stamped into them.
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It's quite common to find stripped bolt heads on old Japanese cars and motorcycles.
Looks like a Phillips screwdriver was previously used on these ignition point screws.
Here's another example:
On a typical Mikuni four-carb rack, there are eight carburetor holder screws.
The torque spec is not always given in the service manual, but they are on there tight!
The first time you use one, you'll immediately feel the difference.
They fit snug and secure, and allow easy removal and correct torquing.
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Standard vs Impact Bits
Impact bits are often called upon when loosening rusted, seized, or over-tightened screws. They are specifically designed for use with impact drivers, which generate axial impacts in addition to rotation.
Standard bits are designed for use with manual screwdrivers, cordless drills, or electric screwdrivers that deliver steady, rotational force without impact. They are best suited for low-torque applications.
Pictured: JIS Impact Screwdriver Bits For Impact Driver
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Can I Use a Phillips Screwdriver on a JIS Screw?
Because the tip will not seat completely, it will cause the driver to slip and strip the screw head when applying pressure. So you should avoid using a standard Phillips screwdriver on a JIS screw.
Conversely, a JIS screwdriver works safely on both JIS screws and standard Phillips screws.
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Notes and Misc
While assembling this wooden motorcycle engine stand, I found that a JIS blade gave much better grip and torque than a conventional Phillips.
#10 drywall screws installed in 2x4 strips.
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Buy A Set
Because they're made in several sizes, you'll want to have a set different-sizes. Here's an inexpensive set from Hozan:
This set offered by Riftwild has magnetic tips and full tangs with solid shafts:
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