Recently got myself an FZR600 and been asking the same question myself, mine came with a 150 fitted so I know it works but not ridden it yet (and the tyre was square and bald anyway)
If you do a google on FZR600 or look at FZR project, this site lists 2 ways to fit a 17" rim but both include new swingarms so not sure if you will want to go that route
Is there anyone on here that can help and take a tape measure to their RD for me.
I have got some headlamp brackets that I am putting on Ebay but I am not sure whether they are of an RD400 or an XS500 and from memory the gap is different.
Thanks in advance for any help