Would Z1000ST forks and yokes fit my Z1000J

[Julian_Boolean]

As above really, there's a set of 40mm 1979 Z1000ST forks and yokes on ebay, would these bolt straight onto my 1982 Z1000J2.

40mm is 2mm bigger than the standard 38mm J forks, my bike currently has an 89 FZR1000 EXUP front end fitted which is too short so the bike tips into corners and lacks ground clearance, the lack of fork offset also makes the steering heavy.

The bike will keep 17" wheels though.

[Ultim8pc]

Anything can be made to fit, but not sure why you'd want them...

[trikerdrew]

As a rough guide I would check the headrace bearing sizes.

Would it not be easier to get longer fork tubes?

drew

[Julian_Boolean]

As a rough guide I would check the headrace bearing sizes.

Would it not be easier to get longer fork tubes?

drew

Checked the headrace bearings and looks like the stem on the ST is biiger than the J, the top bearing of an ST is the same bearing as the bottom bearing of a J

Longer fork tubes would be possible (R6 ones are about an inch longer than EXUP ones, VMAX ones are about 3 inches longer) but part of the problem is that there is little offset in modern yokes, this gives the bike loads of trail which makes the bike very stable but with heavy steering.

[trikerdrew]

Appreciate what your saying about heavy steering. If you raise the rear that would help. Problem is everything is a compromise, unless you bespoke engineer it all

The trick when building a fj12 chop was to use dt125r tubes.4" over IIRC

Have you considered a zr1100 front end?

drew

[Julian_Boolean]

If you mean a ZRX1100 front end then the forks are much the same length as the ones I have, I don't know about the offset.

I'll probably end up buying a set of Z1000J or GPZ1100B forks and yokes and getting spacers made up for a 17" wheel to fit, this seems to be the easiest answer for getting the geometry right, I'll fit emulators in the forks to sort the damping out, it'll mean a drop from 43mm forks to 38mm, but I doubt if I'm going to make 38mm forks flex, my Yamaha FZ750 has 39mm forks and they do not flex.