JIS vs Phillips: why your screwdriver ruins Japanese motorcycle screws
Updated 2026-08-09
If you have ever stripped a carburettor screw or a side-cover screw on a Honda, Yamaha, Suzuki or Kawasaki, the screw was probably fine and your screwdriver was wrong. Japanese bikes use JIS cross-head screws, which look like Phillips and are not.
The difference is by design. A Phillips driver is made to cam out — to lift out of the head above a certain torque, so factory assembly lines cannot overtighten. Put that driver in a JIS head and it cams out early, chewing the head as it goes.
How to tell them apart
Look for a small dot or dimple punched next to one arm of the cross — that is the JIS mark. The head is also flatter in the bottom of the recess, and the flanks are straighter than the tapered Phillips flanks.
A JIS driver sits deeper and grips the flanks instead of riding up them, so it turns tight screws that a Phillips would round off. A JIS driver also works acceptably in a Phillips screw; the reverse is not true.
- — Dot next to the cross = JIS
- — Flat-bottomed recess with straight flanks = JIS
- — Tapered, pointed recess = Phillips
- — Phillips driver + JIS screw = cam-out and a stripped head
What to carry
One JIS #2 driver or bit covers most of the screws you meet on the road, with a #3 for larger engine covers and a #1 for instrument and switch-block screws. A stubby version is worth having for cover screws under the tank.
If you are also carrying a bit driver, a JIS bit set weighs almost nothing and replaces the separate driver. That is usually the lightest way to cover it.
Screws that are already damaged
For a rounded head, a screw extractor bit or a hand impact driver will usually break it loose — an impact driver is a garage tool, but a bit of penetrating oil and a sharp tap on a correctly sized driver often does the job by the roadside.
Replace the damaged screws with hex or Torx equivalents where you can. Riders who work on their own bikes often swap the cover screws once and never fight them again.
The kit, item by item
Reversible screwdriver — JIS/Phillips + flat
JIS #2 is the single most useful size on a Japanese bike.
A 1/4in bit driver with JIS #2, PH2 and a 5 mm flat covers everything.
Where to buy:Amazon
Penetrating oil / water dispersant (sachet or mini can)
Wins arguments with corroded cover screws.
Where to buy:Amazon
Pliers with side cutters
Last resort on a proud, rounded head.
Where to buy:Amazon
Spare nuts, bolts and washers (your bike's common sizes)
Carry replacements for the screws you damage.
Where to buy:Amazon
Questions riders ask
- Which brands use JIS screws?
- Honda, Yamaha, Suzuki and Kawasaki, plus much of the Japanese-derived hardware on other bikes. European brands generally use Phillips, hex or Torx.
- Can I use a JIS driver on Phillips screws?
- Yes, in practice it works well. It is the other direction — Phillips driver into a JIS screw — that causes stripped heads.
- How do I identify a JIS screw quickly?
- Look for the single punched dot beside the cross recess. If it is there, use a JIS driver.