KZ1000 Muscle Bike Build - ZRX Swingarm, ZX9R Fork

Hello all!

Long time member, I just wanted to start a thread to share the project bike that I've been working on for the summer. The project is still going, and as I tackle some of the usual issues with these swaps, I wanted to share how I'm approaching them.

The bike is a 1977 KZ1000 A1. I started out riding on a KZ750 Spectre that I unfortunately crashed into the back of a truck that pulled out in front of me. While in the waiting room at the hospital, I paged through a local classifieds ads and found this bike. Immediately after getting discharged, I went over to look at the bike and ended up riding home with it.

The bike had never been in a pristine state, and was raced in the 80's. so there is a lot of non-standard work done on it. I put some clubman bars on it and rode it for a few years, but I always wanted to do some kind of suspension swap. I really think the KZ 1000 has a muscle bike look to it, so I'm going to try to play that up.

The plan:
- Swap in a front end from a 94-97 Zx9r
- Install a ZRX 1200 swingarm
- GSX-R1000 Rearsets
- Harley Dyna street bob spoked wheels
- New Exhaust
- New Seat
- New Wiring Harness
- Engine Rebuild (Winter project)
- Paint

So here it is at the starting point.

Front Suspension

A lot of forum members seemed to be using the ZX9r forks for their build, so I found a set at the local junkyard. I had a machine shop press the KZ stem into the ZX triple trees and it mounted right up. I've got some more machining to do on the forks, but here's the quick strip down and mock up (try not to judge the motorcycle holding fixtures, I'll do better in the future) :













The ride height is noticeably lower, but even with the 16 inch front wheel and the 1/2" drop with the ZX9R suspension, I believe it'll ride without bottoming out. I don't know for sure, though, because that front tire isn't really rideable. I'll be fixing that soon.

Front Wheel

The front wheel is from a 2013 Harley Dyna Street Bob. It has 25mm bearings, which perfectly match the zx9r front axle. I did eliminate the speedo drive for now, and plan to run just one front brake, though the wheel can run dual. I'm still testing the fitting here, but it looks like you have to run brake rotors with zero dish, which is what came with the wheel. I machined some axle spacers to get the wheel centered. I think it looks pretty good.

Rear Swingarm

Next I went on to fit the ZRX1200 swing arm. The swing arm needed some slight grinding on the right hand side of the pivot point to fit in the frame, about 1/8" off. I'm also in the process on making an adapter to replace the swingarm pivot bolt, which I'll post when complete. Like others have found, the swingarm swap requires that you grind off the rear brake pedal mount and install rear sets. I'm currently machining a few parts for the rear set installation, so that'll come later.





I've got a Dyna 17" Street Bob rear wheel coming my way in the mail to replace the green mag, but this should be roughly the same wheel/tire size in the final product.

I think that is it for now. I'll keep you posted as things continue to progress!

Loving the build so far! Did the ZX9R disc bolt on to the Street Bob wheel?

Thanks! Everything is in varying stages of completion, and there is always more to do, but it finally feels like it is coming together.

The zx9r disc does have the same bolt pattern as the street bob wheel, but there are two issues:

1. The center of the zx9r disc is larger than the shoulder cut in the street bob hub, so you have to self-center the disc. This isn't a show stopper, but just takes a little more care to align the disc.
2. However, the zx9r disc has an offset, where the harley wheel is set up to have a zero offset disc. With the offset, it pushes the front wheel off center, so they are basically unusable in this application.

I'll probably end up using the harley disc that came with the wheel (ugly, but functional and I already have it) or looking for some zx10r discs at the junkyard, I hear they have no offset.

Ok, so I spent the day sorting through the rear sets on the bike. I had previously purchased a set from a CBR600, but when I got them home and looked at them on the bike, the foot pegs were arranged way too far back. So I ordered a set of aftermarket rearsets intended for a GSX-R1000, and they were much closer to what I was going for. I was able to use the master brake cylinder from the CBR set on the new rearsets, so that is a plus.

You can see in this picture the difference of where the foot pegs are located:



So my idea for mounting the rearsets was reusing the top stock footpeg mounting post as a standoff for the footpegs, and then making up a post that could be bolted to the frame through the frame reinforcement around the swingarm pivot bolt. Below is what came off of the lathe.



Next I chopped off the threaded section of the top footpeg mounting post:



And I drilled and tapped it for the correct screw.



Finally, I marked and drilled a 1/2" hole for the mounting post, and bolted it all together.



It ended up being nice and strong, I jumped around on it for a little bit, and it is definitely more solid than what the KZ had before. I may work up a small bushing to go over the original mounting post to make it look the same thickness, but that does it for now. The other side involves grinding off the rear brake mount, so I'll probably end up getting to that next weekend.

cool project lovin all the fab work.

leon

Ok, got an hour to work on the bike tonight, so here's a small update. I did the right side rearset.

Ever wonder how to drill a hole down the center of a rod? Here's what I did. I took a short cylinder or aluminum, drilled a hole in it the size of the rod, then drilled a hole all the way through the size of the drill bit I wanted to use.



Placed on the post



And drill!



It probably isn't perfectly accurate, but it worked out really well.

Here's the final rearset mounted with the CBR600 master cylinder mounted up. I got to test out the seating position and it is just about perfect.



And the bike as it currently sits today.

In my build, I have made my custom spoke wheels using Harley Davidson 40 spoke hubs as the bases. I have lots of measurements in my thread for brake disc spacing (which the ZRX and ZX9R are the same) and have measurements for the rear wheel to fit the ZRX1200 swing arm. I also have developed a drop in swing arm pivot to adapt the arm and have the drawing with dimensions on the first couple of pages. Good luck with the build.

Cory

Thanks Cory, your build thread is an inspiration. I'll actually be using your design for the pivot bolt, I've got it roughed out right now, I just need to drill and tap the bolt holes. One day I hope to give the engine a rebuild like you've been doing, but that may have to wait another year.

-John

Looking good, I like where your going with this.