[clockman592]

I have an 85 Z550 I am in the process of tinkering with. It has single pot calipers. Does anyone know if I can upgrade the calipers to something a bit beefier without modification. If so some advice on which calipers/disks to use would be helpful.

 

[davidr1963]

I’d be inclined to buy a complete front end from a later bike (zxr400, zx6r etc) with a17” wheel, 300+mm discs and four pot calipers.

I’ve done a GPz750 with a zxr400h front end and another with an R6 front end.

 

[clockman592]

I’d be inclined to buy a complete front end from a later bike (zxr400, zx6r etc) with a17” wheel, 300+mm discs and four pot calipers.

I’ve done a GPz750 with a zxr400h front end and another with an R6 front end.

Yep . that was another thought I was working on too. I have seen another chat on here where someone recommends upgrading to braided hoses and better pads which I might do initially but I'm thinking about a new front for better suspension too.did they swap over ok? nice pics, reminds me of my gpz900... back in 89.. lol happy days.

 

[davidr1963]

The GPz (and many other kwaks of that’s era so probably the z550 too) use 52mm o/d lower and 47mm o/d upper, taper roller bearings.

Using eBay or Simplybearings.co.uk, I’ve sourced replacement bearings to suit the diameter of the yokes going on (both 25mm for the zxr400H (not L) and 30mm for the R6).
I’ve not managed to find above 30mm so the zxr400L is out at 35mm top and bottom. The zx6r/Zx9r (G and C models with 46mm RWU forks) yokes are 25mm top and 35mm bottom. My plan for that is to have the lower end machined to 30mm.

Most later kwaks seem to have 35mm/55mm lower bearings but the GSXR Suzukis are all 30mm. There are no doubt many more that will fit but they’re the ones I know about off hand.

All balls racing have a good list although I’ve found some errors.

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[martin-csr]

I don't have any specifics, but some guys have been able to install modern calipers by fabricating caliper mounts.

If you end up keeping the stock calipers, you could install new ss braided brake lines & a master cylinder from a modern motorcycle. I have a single disk front brake on my 81 KZ650-CSR & installed the mc from a Honda CBR500 plus the brake light wires from a KZ1000P police model >> direct fit & same wire colors.