JIS vs PHILLPS vs New JIS Screwdrivers

Some words about Kawasaki screws and appropriate screwdrivers -

The screws on Kawasaki motorcycles that look like Phillips screws are not Phillips screws. They are Japanese Industrial Standard (JIS) screws.

Phillips screws are intentionally designed so the screwdriver bit will cam out as the screws are made tight. This was done to aid the manufacturing process. Using a Phillips screwdriver on a JIS screw is a problem because the JIS screw profile is different than the Phillips screw profile (see first picture below).

JIS screws have a different profile than Phillips screws, and this difference is intended to prevent the JIS screwdriver from camming out. This different profile was built into the design of the screw AND the JIS screwdriver. Using a Phillips screwdriver on a JIS screw is a problem because true Phillips screwdrivers will deform a JIS screw as it is tightened of loosened because they do not properly fit the screw.

Unfortunately, the folks in Japan have redesigned the screws used in their industry. The new screws are not the Phillips design and are not the original JIS design used on the KZ, but they are still called JIS. Unlike the original JIS screws used on our KZ bikes these new “JIS” screws accommodate pointed screwdriver tips similar to Phillips. The first picture below shows the Phillips, the original JIS, and the new JIS screwdriver tips.

Using a Phillips or a new JIS screwdriver on a KZ screw is a problem because neither the Phillips nor the new “so-called” JIS screwdrivers work well on the old style JIS screws. The good news is that Phillips screwdriver tips can be easily made into the old style JIS screwdriver tips by grinding off the pointed tip of the screwdriver (see second picture below). With a little patience, the modified Phillips screwdriver tip can be made to fit the KZ JIS screw extremely well (see third picture below).

Ed

I was not aware of the new version of the JIS driver/screw head. I have not encountered one as of yet. Thanks for this update

Good info 650ed. I would also like to add that not all Philips tips are the same. I find some that fit JIS screws quite nicely, and others that cam out even after grinding off the tip. I have one favorite philips that works better than my JES screw driver. Philips tips do vary between manufactures.

Apparently there waas once a Japanese governing body that determined whether tool manufacturers could call their screwdrivers JIS. That governing body no longer exists, which is why Vessel (for one) no longer refers to their screwdrivers as JIS. From what I've read, a lot of the manufacturers that call their stuff JIS are really making regular, often low quality, phillips screwdrivers.

With all that said, I love my Vessel screwdrivers and won't touch my bikes with any of my "regular" phillips screwdrivers.

I used to use only the screw drivers form motorcycle tool kits as they are JIS, I was told this by a mechanic friend in the early 1980's . I'm still surprised by the amount of bike mechanics that still don't know about JIS screws. I recently introduced a mechanic friend to JIS drivers {vessel} , he's 70 years old and never knew, he loves them and uses them religiously now. I've had my vessel drivers for years and won't use anything else.

This should really be reposted in the FAQ forum.

750 R1 wrote: I used to use only the screw drivers form motorcycle tool kits as they are JIS, I was told this by a mechanic friend in the early 1980's . I'm still surprised by the amount of bike mechanics that still don't know about JIS screws. I recently introduced a mechanic friend to JIS drivers {vessel} , he's 70 years old and never knew, he loves them and uses them religiously now. I've had my vessel drivers for years and won't use anything else.

I bought a 650 engine from a heavy duty mechanic. He said he rebuilt the engine but I pulled it apart anyway to make sure everything was good. He managed to screw up the threads on every single screw.

I wonder if the old Jis driver works on the new Jis screws or will you definitely need a new type of driver to go with the screws, you know what I mean, I wonder if it works one way and not the other?
I have a nice collection of drivers for my 1000st, the Vessel T handles are very handy, made well and strong, I have a few toolkit drivers, a few Kamasa Jis drivers and this Laser set that I've found a stock image of do the job nicely too!

Thanks a lot. I didn't even know those T-handles were a thing, but now I need them.

hardrockminer wrote:

750 R1 wrote: I used to use only the screw drivers form motorcycle tool kits as they are JIS, I was told this by a mechanic friend in the early 1980's . I'm still surprised by the amount of bike mechanics that still don't know about JIS screws. I recently introduced a mechanic friend to JIS drivers {vessel} , he's 70 years old and never knew, he loves them and uses them religiously now. I've had my vessel drivers for years and won't use anything else.

No surprises there...!!

I bought a 650 engine from a heavy duty mechanic. He said he rebuilt the engine but I pulled it apart anyway to make sure everything was good. He managed to screw up the threads on every single screw.

I'm in the middle of going over my sons 1981 650 at the moment, i've already replaced half the bolts on the bike and haven't even touched the engine yet, apparently it was rebuilt about 500 kilometres ago {710 kit} , but the bike has sat for at least 10 years. I removed one bolt from the battery box mount that was too long, the PO had bottomed it out on the frame and kept trying to tighten it up,snapped the head off, then I tried to fit the new battery in and it wouldn't fit, the PO again had fitted too long a bolt down both sides and pushed the inside skin of the battery box in about half an inch. to make it all worse, he'd painted the carbs ,tail light bracket, horn, fork legs and various other parts in 2 pac GOLD...!!! Some people shouldn't be allowed to work on bikes...!!!

Kaylinator wrote: Thanks a lot. I didn't even know those T-handles were a thing, but now I need them.

T-Handle tools, screw drivers and sockets, were THE THING for pit crews back in the dark ages before cordless tools. We had quite a selection of T Handles in the Engine Repair Dept. back in the early days, the Japanese guys were fast with them!

Mike

Hey that's cool I didn't know that! I love my T handles, they're super tough, no handles have any scratches or nicks and they provide a good amount of torque
While we're on the subject of tools, here's two that I got in a big lot and I have no idea what they're for! The screwdriver handle one seems to be home made! Can you guys shed any light?