Mikaw wrote: Appears you have a real mix matched parts lot. You have some from a later Kz1000, possible an LTD. Also I see performance parts, Dyna ignition and copper head caskets. The head looks like a kz1000 and the cam cover is definitely not Z1. I’m not dogging you I’m mentioning it so you are aware of what you have so you get correct replacement parts. You mentioned the goal is not factory correct. Appears you have enough to put together a running bike. My guess is someone put a 70mm (Kz1000) upper on a 66mm (Z1 900) engine, that was a popular period correct performance mod. If you know the cylinders are in need of at least a hone, measure the bore. I’d bet it’s at least if not bigger than 70mm. All good and acceptable for your goal. Please don’t assume you can order all parts based on it being a 1973Z1. Good bones to start with and extra parts. You did good... Ask lots of questions, HardRockMiner knows the Z1 inside and out. Your in good hands here. Have fun.

Yep it’s a mix match of parts for sure and a lot of them are not original Z1.
The cylinders measure 66 mm the pistons he gave me with it measure 68.4 wrist pins are not the same.
I think they just got mixed in with the parts, probably for another bike make model.
Getting a running bike together is the goal. Will worry about all that period correct stuff later.
The guy that I got it from had enough parts to put together one complete bike and probably half of another. He had kz1000’s and Ltd. I think they were about five or six frames, various tanks fairings, swing arms, wheels, jugs, etc. He had an all original KZ 1000 turbo there great looking bike.

By the way, on the gaskets, there are about five complete sets of gaskets, about six or eight head gaskets, split and one piece.

If you want increased performance from your forks there is Race-tech. I got springs and valve emulators. Really improved the front end for me. got rid of the brake dive big time.

That looks like the shocks I have. Regarding the front forks - mine still have the original stock springs and they work just fine for me. They worked well years ago when I weighed 165 pounds and they still work fine now that I weigh about 210 pounds. You can measure the spring length to be sure they are still in spec. The correct spring length is 494.5mm with a service limit of 485mm. Be sure to flush and change the fork oil, and to use the correct amount (measure 396mm from the top of the forks with the springs in and the front wheel off the ground) and be sure to pump the forks several times before measuring to expel and air that may be lurking there. I use BelRay 15w fork oil, and I only do one side at a time to eliminate the possibility of the forks collapsing all the way down. Ed

650ed wrote: First, the KZ650 original rear shocks were toast after about 10,000 (or less) miles. If your bike has original shocks replace them with quality units. I have been using Hagon shocks for more than 13 years and they still work like new. Prior to those I used S&W shocks which also worked great but did not look similar to stock units.

Ed, is this what you have on a bike?
www.hagon-shocks.co.uk/catalog/partdetai...rderdetailid=1529834

I don't see any for sale in USA. What other brands available/good? I would like to stick with "stock" look

What is your suggestion for front? Just new springs? I assume I need to change anyways for my weight. Which brand would you recommend? Progressive springs?

I am little confused because "Progressive" make only one spring. Other makers produce different ratios and provide calculators I can use to figure out for my weight

Yes, they both may be linear but, you get more travel with the shock laid down, look at the way shock angle changed in the 1970's on motocross bikes before they went to monoshock, the later twin shock bikes had their shocks laid down to give the suspension more travel and tunability. Also when trying to work out rear suspension you have to include sag, and swingarm angle or anti squat, the swingarm shouldn't be parallel to the ground, I think, from memory, it should be set at somewhere around 10 to 14 degrees downward. There are a lot of things to consider apart from shock angle.. I'm moving the rear shock mounts on my bike , I won't be buying shocks until I work out the swingarm angle , that's when I'll know what length shock I'll need, actually, I need to work out ride height at the rear before repositioning the top shock mounts, lucky I have a friend that's very experienced with suspension and he has a frame jig, so the frame will be in the jig while all this is done. I'm not doing it to race, just building a race replica {Moriwaki}, my OCD is what pushes me to get things correct. I'm still trying to work out how to get the rake where I want it too, I am using a 17 inch wheel front end with 40mm offset so I'll need somewhere close to 24 -25 degrees of rake, {i have 28 degrees stock}, I can adjust the rake slightly by either raising the rear slightly, or dropping the forks a touch. Lots and lots of calculations, I'm a classic over thinker....!!

What State are you in ? I found this pic on the web with a small description of its mods for period 5.

"KAWASAKI GPZ100/Z1100 P5 RACE BIKE:37mm CR carbs, ZXR swing arm, brembo brakes, Manta disc's-forks-brace-triple trees-, CBR 600 legs, Scitsu tacho charger, wets and wheels , spare Ohlin's shocks, Dyna Ignition, Dyna coils , Dyna leads, Moriwaki cams-spring-retainers, Moriwaki 11.5:1 pistons, light crank, modified oil system cooler"


Try contacting someone like Rex Wolfenden from T REX racing developments in Victoria, if he doesn't know it, it doesn't exist....
T-Rex racing developments 03 9457 5411

I agree with Ed in that the Kawasaki engineers got the chassis design right with the 650. The steering head area of the frame is nicely reinforced with stamped metal gussets and is significantly more braced than the 900 and 1000 frames in that area. Upgrading the shocks, steering head bearings, and maybe the fork springs would be good places for a few bucks during your rebuild.

I've put more than 61,000 miles on my 1977 KZ650-C1 and highly recommend the following:

First, the KZ650 original rear shocks were toast after about 10,000 (or less) miles. If your bike has original shocks replace them with quality units. I have been using Hagon shocks for more than 13 years and they still work like new. Prior to those I used S&W shocks which also worked great but did not look similar to stock units.

Second, be sure to buy quality tires. I use Pirelli Sport Demons and they work extremely well. I'm on my 3rd set; they last about 7,000 miles per set.

One other thing - take some time and perform ALL the maintenance listed in the Kawasaki Service Manual. At that point you will have eliminated many small but important issues that may have been neglected. Things like fork oil, brake fluid, etc. can help make a bike perform great or poorly, and if those things have been neglected (and assume they have been) the bike will not perform nearly as well as it should and won't be much fun to ride. The Kawasaki Service Manual has a chart of all the maintenance items and describes how to perform them. Also, assuming your bike has all the original parts, such as airbox, exhaust system, etc., keep those parts on it! The KZ650 was engineered by true professionals and has everything it needs for highly spirited, or even mature, street riding. Also, forget making any changes to the swingarm, frame, forks, etc. especially for street riding! Unlike some earlier KZ models, such as the KZ900, the frame, swingarm, forks, etc. are easily more than sufficient for highly spirited street ringing. These bikes are engineered extremely well.

Below is a picture of my 1977 KZ650-C1. Ed

After a couple of years without a old Kwaka race bike, I am toying with idea to build one up.
Have spent a bit of time trawling through this forum and the net to get some ideas.
I have a 81 GPZ1100 frame and most of the motor in the shed and thought I would utilise it.
As it would be log booked for Period 5 (bikes from 1st Jan 1973 to 31 Dec 1982) racing in Australia, there are a few rules I need to follow to be eligible.
So at this stage, I am looking at a ZRX swingarm as I can run up to a 5" rim. Hopefully they will allow it, otherwise I will have to go with something more period friendly.
We are allowed 41mm forks, so I was thinking that a ZR750 front end would be good. It was mentioned that it is a straight swap. Does anyone know anymore about it?
There are a couple things I am not too sure on, and I was hoping someone might be able to help or point me in the right direction.
Firstly is frame bracing. Anyone know where is best on these frames or if there is anyone in Australia to see about it?
Secondly is brakes. They need to be from the period or replicate those manufactured in the period. Does anyone know what the best from that time frame is, that are relatively easy to source?
Any info or advice is welcome.
Once I get everything figured out and parts sourced, I will do a build thread as well. Thanks.

I am reading all I can here on forums, digesting as much info as I can.
I will be going through frame up restoration, frame will be powder-coated.

Initially I didn't think about making changes, but reading here I am considering it especially that I do want to tinker/weld
Another question is rear swing arm. I read somewhere that those were weak from a factory prompting aftermarket versions. So, I was wondering if it was a DIY to maybe reinforce that somehow as well "while in there"

If you have any pointers, pictures, drawings, I will appreciate it.