Dear MOby,

Is it true there are special screwdrivers for working on Japanese motorcycles? Are you telling me it’s not my fault, or my Harbor Freight Phillips screwdriver’s fault, why we have such a frustrating time with all these screws on my old GS550? Really?

Phillip S. Driver
Swearjar, AL


Dear Phillip,

Wherever did you hear such a thing? Perhaps you were reading the comments after “Church of MO” two Sundays ago, in response to Gabe Ets-Hokin’s tortured tales of working on his old Honda? It is rather hard to believe, as one commenter mentioned, that after all these years of mangling Phillips screws on Japanese bikes, more people (many of them professional mechanics) don’t know about JIS screwdrivers – Japanese Industry Standard.

Looking at a JIS tool next to a regular Phillips screwdriver, most people are hard-pressed to tell the differences, but they are definitely there. Ninety-percent of the time, a regular Phillips will work on a JIS screw; but it’s that other 10% that gets us swearing, then throwing things – those tight screws holding on your carburetor float bowls being particularly devilish once they’re past about two decades of non-removal. That’s when the right tool can make all the difference. The right tool is a JIS screwdriver, which just fits better in a JIS screwhead and is designed to let you apply more torque than a Phillips driver.

Sometimes a dot will let you know you’re dealing with a JIS head. But not always… note how shallow this one is compared to a Phillips.

At Instructables.com, we learn: The Phillips system was invented for use in assembling aluminum aircraft, with the object of preventing assemblers from tightening screws so tightly that the aluminum threads strip. The driver will “cam out” before that happens. The Phillips driver has four simple slots cut out of it, each slot is the result of two machining processes at right angles. The result of this process is that the arms of the cross are tapered and has slightly rounded corners in the tool recess. Phillips is designed so that when excess torque is applied it will cam out rather than ream the recess and destroy the bit.

Japanese Industry Standard: Often improperly referred to as Japanese Phillips. Commonly found in Japanese equipment, JIS looks much like a Phillips screw (and even more similar to Frearson), but is designed not to cam out and will, therefore, be damaged by a Phillips screwdriver if it is too tight. Heads are usually identifiable by a single raised dot to one side of the cross slot.

Most people and companies outside of Japan have absolutely no idea what they are. With the similarity in appearance to the Frearson and the Phillips the screws are often damaged in removing and installing with the wrong tools. JIS tends not to cam out like Phillips. The JIS driver can be used on Phillips quite easily but not reciprically (sic). Drivers are not easily available in North America, try your local RC Airplane hobby shop. Most RC Helicopters use JIS screws to mount the propeller. JIS-spec cross-head screws are generally marked with a single raised dot or an “X”. JIS always fit Phillip fasteners, but because of slight design differences, Phillips drivers may not fit JIS fasteners. (unless the tip is ground down a bit).

This Vessel Megadora 980 Impacta P2x100 #2 Cross Point Impact JIS Screwdriver, which combines an impact driver with a screwdriver, could’ve saved me untold grief as a youth. An internal cam mechanism turns the tip 12 degrees per hammer blow.

The JIS is not a miracle tool for really stuck fasteners on old Japanese bikes, but it can make a huge difference. Luckily, most manufacturers have seen the light in the form of the hex-head fastener and the Torx, and while they can also present problems, they’re nothing like as frustrating as trying to remove a stubborn Phillips-head screw with not-quite the right tool.


Send your moto-related questions to AskMOAnything@motorcycle.com. If we can’t answer them, we’ll at least make you feel temporarily better by thinking you’re talking to somebody who cares even if we don’t. And remember, only the Pope is infallible. But we probably know more about motorcycles.

Recent Ask MOs:
Is Clutchless Shifting Bad for my Transmission?
What are Tire Balancing Beads?
Why Do Nails Only Puncture REAR Tires?

  • Walter

    That was informative— thanks.

  • TheSeaward

    Vessel JIS screwdrivers are expensive, but I would buy them again in a heartbeat.

    • RMP52

      I bought an impact driver set from a Honda dealer many, many years ago. I was always amazed at how easy it would remove screws that my Philips would round out. It wasn’t until years later that I found out about JIS screws, and realized why my driver set worked so well. Of course I have a full set of JIS screwdrivers now, but I always wondered why they haven’t been mentioned more often. Any article about working on Japanese bikes should include a primer on JIS screws. Thanks John for pulling the curtain back on this little known “secret”.

  • Matt O

    Ha! I’m shocked and amazed that my comment last week inspired an “Ask MO”

    • Jon Jones

      Genius sneaks up on us at times…

    • john burns

      Hey man, I do an Ask MO EVERY Monday. Feel free to inspire me whenever you can!

    • Don Orton

      Hey – I think it was MY comment that was the inspiration! I like to think of myself as an inspirational person…

      Oh, I guess yours was first, Matt. I elaborated the “point”.

      • Matt O

        Plenty of credit to go around

  • Jon Jones

    This stuff really matters.

    And Angels weep at my knowledge of fasteners.

    Good piece.

  • Dave G

    There is also one called Reese Prince that looks like phillips but not.It was used in England back when I live there in the 60s.Don’t know if they still use them now.I still have a few in my toolbox.There was also sockets they call witworth (not sure on spelling)Something like that.

    • John A. Stockman

      Yes, my grandfather had a set of Whitworth tools for the old Brit bikes, like my uncle’s Sunbeam and the various Norton, Triumph and BSA machines he worked on. Reed Prince is the “other” Phillips! Well, not really. Grandpa also clued me in to the JIS screws and drivers. He showed me the difference in fit with the JIS and Phillips drivers. My friends would want to come over so they could use my set of JIS screw/impact drivers on their Japanese bikes. I would NEVER let them borrow them because my grandfather gave me his set before he passed away, along with the Whitworth sets and lots of other old-school tools. I came across many buggered JIS screws that had Phillips drivers used on them, but even a proper JIS driver could sometimes get them out…not always though, some were too far gone. I know folks who still don’t believe me when I tell them there’s a difference! Maybe this article will clue them in, thanks!

  • Toldyouso

    Anyone still putting Phillips screws into ANYTHING during manufacture after all the grief they’ve caused us for decades when we have Torx for instance should be incarcerated. For a long time.

    • brunssd

      You ought to have to regularly deal with the horrendous Robertson screws that Canadians are so very proud of.

      • Toldyouso

        I admit I don’t know what those are. Would it be something worth looking up?

        • brunssd

          You’ve no doubt seen them, they’re known in the States as square drive.

    • Campisi

      “But, but Allen-”

      No.

      “But-”

      No!

      “…”

      “… But-”

      No.

  • Tim Sawatzky

    Amazon has lots of JIS sets for not that much money. I ordered a set of 4 and had ever size I needed for my old cb650. They do work a lot better, if you have a Japanese bike you just need to order a set so you don’t strip screws by accident. I always had a problem of Philips slipping and leaving a sharp bur on the top of the screw, then the bur can scratch things, or a cleaning cloth catches on it. The JIS screwdrivers prevent that.

  • STAN

    Awesome data!Thanks man!

  • Jamie Daugherty

    Amazing…I’ve told people this for years and nobody believes me! Every time I go to Japan I pick up a couple of crossed-recess (the technical name) screwdrivers.

    • John A. Stockman

      I show people my JIS set and they think I’m making it up still. Fortunately, my grandfather had a set that I inherited when I was just getting my first street bike, a KZ250. He told me about them decades ago and I used them when I had to do any work on my Honda Mini Trail 50. He’d tell me “don’t use a Phillips on those screws!”

  • Jerry

    I bought one of these JIS tools back in 1973 to work on my Honda CB750.

  • Juliet Bravo

    JIS screwdrivers on Amazon. Not expensive.

  • mog
  • Patriot159

    If you grind the tip down about 10% on a Phillips driver it does a pretty good imitation of JIS.

  • Rightwheel

    One would almost think the Japanese would let the customers in its largest market in on these little engineering secrets.
    I always knew, from experience, that a Phillips would “cam out”, but I never knew it was an intentional design feature. Thanks, Burns.