TOPIC:

I have a 1981 KZ1000J and I want to do a front end and swingarm swap. I am looking at a 1990 ZX7 because I'm broke and it's really cheap.
The question I have is, would it be silly to do this swap? I am assuming the ZX7 front forks and swingarm are more advanced, being nearly a decade older, but I don't actually know much. The tires are different, the brakes are better, and the electronics and controls are a cleaner looking.

Here is the information I have so far:
All Units In mm

KZ1000J 1981
Front Forks
Top Bearing Set
Inner Diameter: 25 Outer Diameter: 47 Width: 15
Bottom Bearing Set
Inner Diameter: 28 Outer Diameter: 52 Width: 16
ZX750 (Ninja) ZX7 1990
Inner Diameter: 25 Outer Diameter: 47 Width: 15
Bottom Bearing Set
Inner Diameter: 28 Outer Diameter: 52 Width: 16

So, as you can see, the forks are identical in the sizes above, so the swap should be very simple. The swingarm has the same axle size, so bushings will be the only thing I need to make that happen.

Here is information on the tires:

ZX7
Front tyre: 120/70-17
Rear tyre: 180/55-17
KZ1000J
Front tyre: 3.25-19 which converts to 100/90-19
Rear tyre: 4.25-18 which converts to 110/90-18

So, I will have much wider tires on the ZX7 forks and swingarm. It is also my opinion that the big 19 inch tire on the KZ1000J looks way too big.
I am new to the forums.
I am looking for knowledge on fork quality, and also, if anyone has any information on fork tube lengths, I would appreciate it; I can't find information on the fork lengths anywhere.

ZXR fork yokes will need the stem swapping due to the differing lengths of the headstock and the 750 forks are around 60mm too short so will need lengthening to stop the exhaust dragging on the floor and dangerous handling above 100mph. (remember you have to account for the decreased wheel diameter also in the height calcs)
The swingarm is too wide at the pivot so will need slimming in that area and the chain alignment will need addressing,
If you have access to a machine shop it won't be too difficult and once done correctly you should have much improver handling.

I have a 89/90 Zx7 front end on my '78 1000. No stem swap or bearing swap necessary. It was a 100% bolt on affair. Even the steering stops work perfectly.

The fork length and 17" rim will lower the front end some but not as bad as newer USD forks.

Just my experience.

Later, Doug

Could I get a photo of the ZX7 front end on the KZ? I am trying to decide between ZX9 94-97 USD front end and the ZX7. It's only half an inch shorter, plus the wheel difference. I don't want to do USD forks, but I don't want to be dragging my V&H.

The best pic I have. I can take a measurement of my V&H header to the ground on mine if you'd like.

Later, Doug

Awesome, that looks badass! I'm waiting to hear back about the pricing. Glad that I can see it before I try to do it.