1981 KZ550 Cafe Racer Build

I am planning to turn my 1981 KZ550 LTD into a Cafe Racer. I know that there are better models to use as a base for a cafe racer, but this bike is sentimental to me, and time and money aren't a consideration. I'll give a bit of back story on the bike, then lay out my objectives for the build and what plans i have for it currently.

History:
I purchased this bike back in early 2011 when I was 19 years old. It was my first vehicle I had ever owned. I was attending MMI at the time with the ambition of being a motorcycle technician. Traditionally I am a Harley guy, but I didn't have the money for one of those working a job flipping burgers while attending school. I found this bike on Craigslist for $400, and figured it would be a great starter bike to learn to ride on. The bike had been sitting in a storage unit that went unpaid, and the storage place was selling off the unit. The plates on the bike were dated 1998, So i figured it was safe to assume that the bike had not run in at least 13 years. We got the bike home and i tore into it, cleaning and rebuilding the carbs, replacing the battery, Cleaning the rust out of the fuel tank, replacing the tires, rebuilding the brakes, replacing all of the dry rotted rubber components. After a few weeks of work (had a low budget at the time and had to keep saving to buy parts) I had the bike up and running like a champ. I finished school, moved out of Dad's house, and landed a job wrenching for Harley Davidson at a dealership in TN. Not long after I upgraded to a bigger bike, a 1997 Harley Sportster 1200 Custom, and my old Kawasaki sat neglected for years back home at Dad's house in Arizona. Getting my little 550 to Tennessee wasn't a big priority at that point in my life.

In 2013, My twin brother and I took a road trip back out west to visit Dad. I figured it was a good time to bring the Kawasaki back home to Tennessee with me. Neither my brother or I had a truck at the time, so we had to find a way to cram the bike into his Mustang. I took the whole bike apart, cleaned it, and wrapped it all up and we got it to fit. Then we drove the 1,700 miles back to Tennessee in a car that was pregnant with a motorcycle. The bike has since sat in a million pieces, again neglected. I didn't have enough money or tools to start the build that I had in my mind, and I would not settle for less than my vision. I discovered that Wrenching on motorcycles wasn't a lucrative as I had originally imagined and I needed to go back to school to do something else.

Fast Forward to 2019. I have now moved up to a place in my life where I can start on my Cafe Racer project. In the last 2 years I had graduated from college, and have been working the big job and improving my financial situation. I am finally independent, living on my own with a decent income. I ended buying one of my dream bikes, a 2009 Harley Davidson Night Rod Special (still have the Sportster too). It is a great looking and running bike, in basically new condition. I ride it all over the place. I started to realize the shortcomings of the Night Rod after taking it on The Dragon, hwy 129 (which I live 30 minutes from). The bike has a ton of power and looks great, but a long wheel base and raked out front end don't do much good trying to go through the twisties. Suddenly I had a serious itch to build the neglected Kawasaki that is currently sitting in my crawl space, in various plastic tubs. I needed a bike that was nimble and light. The Sportster is a decent 2 up riding motorcycle with saddle bags and a luggage rack, the Vrod is my baby dream machine drag racing monster, and my KZ will be my light and quick canyon carver.

The Build:
As I stated in the intro, My bike is a 1981 KZ550 LTD. I know that it would probably be cheaper to sell the bike and get something more modern that is faster and yadda yadda, but hey.... what's the fun in that? With this build money is no object. I can fabricate and machine anything I need. The goals for this build are to increase engine performance, overall bike handling, and braking. Essentially try to squeeze as much performance out of the bike as possible. The catch is: I like the vintage styling of cafe racers. This means I wont be upgrading the front forks to USD forks, and I will be ditching the mag wheels for some spoked rims. Listed below are the current plans I have for the build.

Engine:
-GPZ cams
-K&N Pod Filters. (I know the stock air box is arguably the better performing route, but to keep with the trimmed down cafe look, I'm going with pod filters)
-Wiseco 615 Big Bore kit
-Thermal Barrier Coating on the tops of the pistons, Combustion chamber, Valve Faces, and Exhaust port
-Titanium Valves
-GPZ oil pan and cooler
-Custom Exhaust (possibly keeping with a 4-1 exhaust, but I do like the symmetrical appearance of a 4-2. Plus it would keep the bikes weight more even on both sides. I think if i go the route of doing a 4-2, I will have a crossover equalizer tube connecting the headers, which should allow me to have increased scavenging similar to a 4-1. This is one area that i need to do some more maths on. Either way, new custom built exhaust that will be ceramic coated inside and out. This will keep heat in the exhaust gas and reduce the amount that is radiated off the pipe.
-New Performance Ignition Coils (recommendations Welcome)
-New Performance Ignition Wires (recommendations Welcome)

Suspension:
- Progressive Front Fork Springs.
- 17" Warp 9 Supermoto Wheels (I love the spoked supermoto wheels. They should be lighter than the old KZ550 mags. I will probably have to machine a new axle and wheel spacers. On Warp 9's website they have a wheel configurator, but it only has dirt bike models, which makes sense because supermoto bikes are converted dirt bikes.)
- Dual Disc Front brakes (considering getting Brembo Brakes, or maybe sourcing some brakes off of a modern ZX6R I will have to fabricate a mounting bracket to work with my old style forks)
- Rear Disc Brake (Again, I will have to do some fabrication to make a mount for the caliper. Also considering sourcing from a ZX6R or going with Brembo)
- Dual piggy back Fox Shocks
- One potential idea would be to swap out the swingarm to something that is lighter like the Zephyr swingarms. Not sure how much real benefit there would be to this conversion for the headache involved.
- Top Loop Cafe Racer Frame conversion
- Clip ons

Anyways, that's where I am at with it right now. Any advice or input is appreciated. I know that for the money I could easily just go and buy a sport bike, but where is the fun in that. I have no intention of selling the bike and getting something else. I will continue posting updates as things progress with the build. Areas I can see being an issue is with getting the right hubs on the supermoto wheels, and getting those to play well with the brakes and the swingarm/forks and the axles. I figure sprocket spacing isnt a hard problem to fix. The other issue I can see coming up is getting an aftermarket speedometer to work properly.

Sounds like a big project. Funny thing is that a lot of the mods you are describing are already on a stock 81 KZ750 LTD, interesting that the 550 is so different. So, you might be able to get some donor parts from a 750.
They already have dual front disc - your fork has the holes for the right side hardware.
They already have rear disc - might be able to use some of the 750 hardware if you don't replace the swing arm
Not sure what the back of a 550 frame looks like, but the 750 frame is already basically a loop that extends to the back of the seat.
The 750 4-2 exhaust has a crossover

I'm just about done with my café(ish) 750 project. I highly recommend texavina.com/ for a seat if you want something that uses all the stock hardware.

Take lots of pics and make sure to hit the insert all button so that they show up as big pictures rather than those little thumbnails that you have to click on.

I had already purchased wheels off of a CSR that are spoked and have a rear disc brake. They are a 16” wheel on the back and 19” up front. The original plan was to buy new 17 or 18” rims for both and lace them up, but I have struggled to find aftermarket rims that support the 48 spoke pattern. Then sourcing decent brake calipers has been a chore too. The hassle of trying to source these parts and figure it out is what ended leading me to consider just doing Super Moto wheels. I can buy brand new parts and they will perform better than the old OEM stuff I have to source and refurbish. The Super Moto wheels will be lighter, the brakes that bolt up will be lighter, and I will be able to use modern radial tubeless sport bike tires. I guess the overall idea is that the parts are easier to find, and they will have less unsprung weight, which should improve handling.

Congrats on your first build, and congrats on being an MMI Grad. I graduated from AAI back in 1985, and been and been in the motorcycle and automotive industry ever since.

Like a painting, you will need to know when to leave the last stroke off. As stated above, the canvas you are starting with, in my mind, is one step above the shaft drive 550 and not ideal, but you have what you have, and there will be a lot of work ahead of you. Not trying to "harsh your groove", but there are other 550 platforms that would give you a better start. I applaud your efforts, and wish you luck.

Engine building has a lot of history, so this will be the easy part. ZX550 Cams are plentiful and will work. With the 615 Web Camshafts or Megacycle Cams will work but slotted gears are needed. I'll stop here, because you know what you want, and can fab stuff others like myself cannot.

I look forward to reading about your progress. there is a lot of talent here and they will chime in for support.

Great story and sounds like a great project! I'm really looking forward to seeing the photos. My first though was "wheels" when you wanted to have it handle better. I like the sound of wire wheels on a 550. That'd be rare!

I think the biggest problem you will face on making the Ltd. look like a cafe bike is the very high position of the steering tube, and the very long fork tubes that that leads to needing. All of the Kz550's have a huge amount of travel... like Kawasaki thought everyone was going to make dirtbikes out of them.

The Tk22 carbs are very nice and easy to jet for pods. On the highway and twisties, the pods will definitely feel faster if not actually faster. The only downside of the 81 head is that the intake runners are smaller than on the later gen heads. That limits the carb options.

But I think I would focus on the handling first anyway. If you're looking at places like the Dragon, then the 550 probably has enough engine (for me) as is. Obviously, you can go with the 615 kit later if needed. (I was still typing when Corey posted. He is the guy when it comes to motors)

On the fork legs and brake issue, it has come up before, so you may want to know... The dual disk models used smaller disks so even though the single-disk forks have locations for calipers on both sides, those locations are too far away from the axle for the pads to line up on dual-disk wheels. I realize you are getting all new wheels, but in case you take measurements for a factory disk or somehow end up with forks from a dual-disk model, be aware the caliper locations are different and the disks are different diameter.

Interestingly, even though the Ltd had a very different frame, I think the rear shocks are about the same length as the standard model, in case that ever comes up.

I think there are quite a few users here that have gone to the Acewell speedo-tach combo. If I recall, one of the sensor options for speed are to sense the bolts on the brake disk.

Corey, didn't the MOMBA bike start out as an Ltd.? I thought it was something crazy like that.
And I think they would have used the airbox if it was faster, so ...

loudhvx wrote: Corey, didn't the MOMBA bike start out as an Ltd.? I thought it was something crazy like that.

Yes, MOMBA 1 was a, but MOMBA 2 was an 84 ZX550.

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