Front forks on different models

I swear the history of this KZ1000 I got seems more like a who's-who of all the different models. I received my new Clymer book for the correct year (1981) and have been looking through it. Last night I noticed that there are two different style of front forks for the 1981 models... one where the axle is capped on the end of the forks (J), and another where the axle is capped to the front side of the forks (K and M). My bike is a model J, but it has the K/M style forks on it.

I'm not too concerned over something like this, and it actually matches along with my trend of upgrading the bike to the LTD model options, but I am curious if there is any advantages, or differences in performance between the two styles? And was the side-mount style ever used on the 1981 Standard models, or is this yet another thing that a previous owner swapped out?

That's known as a "leading axle" fork. Having the axle ahead of the centerline of the fork vs. at the bottom of the fork and therefore in line with the centerline of the forks changes the steering geometry. On bike originally equipped with leading axle fork this may be counter-acted by the relationship between the fork tube holes and steering stem hole in the triple trees or by the rake of the steering neck. If, however, the lower fork tubes are not those that which originally came with the triple tree, your bike's steering geometry may be affected. You can google "leading axle" forks to get more detailed info on the subject; there's quite a bit out there. Ed

For all I know, this could have been one of those mid-year changes that doesn't show up in the normal manuals, or someone may have swapped the entire front end, including the triple-trees, or any combination in between. Once I get it on the road, maybe I'll run across some other riders, and I can compare bikes side-by-side.

Hopefully this will be the only section of the bike that I have any serious questions about. I'm changing out the entire electrical system, and I have two complete 1981 J engines from which to compare and rebuild. The rest of the frame is getting chopped and rebuilt to restore it to stock condition, so the steering is about the only part I haven't gone over yet.

No eBay APP ID and/or Cert ID defined in Kunena configurationI doubt that Kawasaki would've put leading axle forks on a 1000-J, so somebody probably swapped them.

A Kawasaki factory service manual is preferable. Here's one that appears to be in very good condition. I'm pretty sure it is correct for your bike. Kawasaki manuals have a model application chart on the back cover, so if you decide to get one, make sure yours is on the list.

I actually have the PDF copy of that manual, I may have to see if it gives me any exact specs. From looking around, it appears that it may also be possible the PO swapped the bottom part of the forks without changing the actual tubes. This could be a real nightmare. I think once I get the frame stripped down, I'm going to take the parts over to my local KAW dealer and see if I can enlist the help of their parts guy. I was told he's pretty knowledgeable about the older models, but I haven't met him yet... Hopefully he's one of those helpful types, because I get the feeling I may need to measure every part of the forks to determine what is original.

I've been comparing part numbers today to try and get this figured out...

On my 1000J, the triple-tree uses 44039-1035 and 44037-1055
On the 1000K, the triple-tree uses 44039-1036 and 44037-1057

From what others have said, minor number changes are usually just different paint jobs, and the two parts *appear* to be the same (unlike the P and M models which have obviously different trees)? In fact, the parts diagrams between the J and K forks seem identical except for the lower tube.

So moving on for the moment, I have been trying to nail down the head rake angle used on these two bike... I would assume if they are using the same triple-tree, and both have the same rake angle, then the bottom tubes are interchangeable despite the difference in axle location. So far I have found info that suggests 27 and 29 degree rakes were used in 1981, but I can't find any references that give me the hard numbers of which angles were used on which models. Any chance someone can help me with that, point me to a solid source for both the J and K models?