The impact screwdriver pattented by Vessel.


Every time the Phillips screwdriver you have been using for the last 30 years cams-out and ruins a perfectly good screw could have been avoided by using the proper tool, a JIS screwdriver.

The screw on our bikes are made with the Japan Industrial Standard (JIS) which in this case tries to avoid cam-out when a lot of torque is applied, the opposite of the Phillips standard.


For a very informative article on the subject of screw standards go to Instructable. For those who prefer to watch videos MC garage and a few other cover the subject.


There are many Japanese tool brands and even a few specialized in screwdrivers (VESSEL, ANEX, SUNFLAG,...). Curiously outside of Japan it was difficult to find JIS screwdrivers adapted for Japanese motorcycles.


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JIS Screwdrivers Vessel Megadora

  • The Vessel Megadora is very good I think (I use them), it has a good hand grip, a steel end to hit the screw to ungrip them, the ジョーズフィット(jaws fit) gives the head a very srong resistance to cam-out, and an hexagonal 12mm grip for a spanner.

    The Vessel Megadora comes in three sizes:

    • + #1 for small screws until M3
    • + #2 for screws M4 and M5, in two length 100mm and 150mm
    • + #3 for M6 and M8. This is the size we use the most.

    At least #2 and #3 are needed. Do not try the #2 with M6 screws!