KZ1000 motor in a 650 frame, what would I need?

Anyone here done this? Or know what it would take? I've seen a couple bikes on the web that are set up with the 1000 or 900 motor in the 650 frame so I know it's possible. I've got a line on a 1000 motor to replace mine with bad rings in #1, would end up costing me a lot less to get the motor than to put a big bore kit in my 650, so I'm really considering the swap but want to get some opinions on how difficult and what type of frame modification would be required to make it work. Obviously I'd have to gusset the frame, and I'm assuming stretch the motor mounts. Other than that, does anyone know if sprocket placement would be problematic? Or if the frame would need to be stretched at all to accept the 1000 motor?

hey axton, im not sure on the frame mods, other than the gussets and different motor mounts. I do know that you will have to pull the 900/1000 motorto get the valve cover off. Other than that im not sure.......oh ya, it will haul major a**.....lol

If I remember right someone did this and posted on it about 6 months ago. Very shiny bike if I recall. They had to cut the frame and widen it to accommodate the 900 engine. It would be some work, and I'd lengthen the swingarm and install some kind of a seat stop to keep you on the bike.

One of the guys over at kz650 info sent me a link to an archive post here where someone was talking about how they went about stuffing the motor in. Said they didn't have to cut the frame, just had to work the mounts and gusset the bejeezus out of it! Don't think I'd stretch her any, but would definitely brace the swing arm (or do a boxed swinger swap). Time will tell!!!

if you do the boxed swingarm swap, i would go with the gs 1100 arm, i have seen them on the 650's.

This is form kz650info.com

I just saw that picture of the GPz1100/z650 bike for sale in the UK - a very nice job indeed.

I started constructing a similar bike early last year, using a 1980 Z750 frame (basically identical to a 650 frame), and a Z1000J motor (fitted with 1100 pistons).

This bike has been built to use in local Historic racing, in a class known as 'Forgotten Era' - basically its a vintage Superbike class, and consists of production and GP bikes made between 1972 and 1980.


I managed to squeeze the big Z motor (which has the same external dimensions as the GPz series) into the 750 frame without too much difficulty. The cam cover has to be removed before the engine can be squeezed in, but originally I though the cams would have to be removed as well. They don't, which was a nice surprise.

A number of custom engine mounts were constructed from 10mm alumnium plate. The sump clears the lower frame rails with less than 2mm clearance each side, and there is less than 1.5mm clearance between the very rear of the motor and the swingarm (I am using a GSX1100 swingarm in this bike). I had to use a ZZR1100 front sprocket, which has the same spline pattern as the Z1000J motor, but is has a 19mm offset, so the chain lines up with the rear sprocket just nicely (less than 5mm clearance from the frame tubes - check the photos).

Tom
After I looked around awhile I see your a member over there.

Here's a picture of that same GPz/Z650 I believe:

After being schitzo about it for the last couple days I decided that the prospect of having a 1000 cc stuffed in the cafe is just too bad ass of an idea not to attempt. If all goes well I'll have the motor in hand by next week... I'll start a project thread then. Cheers!!

Go scitzo go

And I thought I was going out by plugging a 750 into my 650. I am looking forward to this build.