Why is wrench size different for metric bolts?

The problem you ran into is the fact that there are a number of different standards for bolts that use metric threads, and the bolts and other fasteners on the Kawasaki are Japanese Industrial Standard (JIS). The confusion is caused by the fact that JIS fasteners use the same thread sizes as other metric fasteners, but some of the head sizes are different than those of other metric fasteners. I first encountered this issue when I was buying stainless bolts for the passenger footpegs on my KZ650. Those bolts are 10mm 1.25 pitch with a 14mm head. The only 10mm bolts that use a 14mm head are JIS bolts; all other metric standards use larger heads on 10mm bolts that will not fit inside the passenger footpeg mounts because of the shape of the mounts. I eventually got the correct size JIS stainless bolts from a place in Great Britain, but it wasn't an easy thing to find.

Below is a link to a chart that shows the head sizes for different flavor "metric" bolts. If you are looking for a specific size bolt maybe I or someone else on this site can help you find it, but you will find that the JIS bolts may be more expensive than bolts you find at the local hardware store. Ed

www.boltdepot.com/fastener-information/b...-bolt-head-size.aspx

I've never seen metric threads with SAE heads before. I do know though that if you go to the hardware store the common metric hardware uses 11mm, 13mm, and 15mm hex sizes.

Same thing happens on import cars, honda, toyota etc. even your new domestics do it (15mm head on 12mm bolts on a chevy) that's why as long as the structure of the bolt is fine (no pitting/corrosion on the bolt body) i keep them all, have two five gallon buckets full.

Also hardware store stainless bolts have grade markings on them, so if tou feel like removing the marks and polishing them up, you COULD cut the hex size down as well

Stainless bolts can be polished to a mirror finish if one has the time and the correct beer inventory. Ed

kidkawie - great idea! Thanks.

Ed - I bought a bit of stuff that I knew would be difficult to find in hardware stores - like some of the long 6x100 head bolts (I was missing 1 of 2) and some others - from Bolt Depot and I thought I remembered some of the options being JIS spec. Thanks for the info.

I did buy replacement front and rear foot peg bolts but I haven't tried them yet but now I know they will not work. I had not thought about the head size for those. Ugh. Guess I'll be searching for some JIS spec replacements.

Thanks for the knowledge Gents!

Whenever I do a restoration the first thing I do is buy extra hardware and send it out with the originals to be replated. Nothing worse than needing a few bolts in the middle of a project.

I use a Caswell's zinc plating kit to clean up the original hardware. I'd much rather recycle the high quality original hardware than replace it with aftermarket.