wrote:

Hi Ed, I know from reading previous posts of yours you don't think they are needed, yes the 650 is very stable, I have fitted dampers to every bike I've owned that didn't come stock with them. Have you ever had a tank slapper ?   I have, one bad enough to dent my tank with my thumb, broke the steering lock tab on a 750 Honda back in the early 1980's at speed, frightened the poop out of me, have used them ever since, Think of them as an insurance policy...

  Besides this is my sons first bike, just being over cautious...



 

I asked because some folks believe they are a cure for speed wobbles even though the speed wobbles may be an indication of a serious problem that needs to be addressed.  My 1977 KZ650 developed bad speed wobbles several years back.  The problem ended up being bad Michelin Macadam tires.  I found the problem after replacing the swing arm bushings, steering stem bearings, shocks, etc., etc. Replacing all those items slightly dampened the problem, but replacing the tires made the problem absolutely go away at any speed.   It appears that the bike in question does not have any wobble so the damper is not being installed to try to correct an existing problem; that's good.  That's why I asked.  Ed

wrote:

This is the jig i made for shock mount location.
Adjustable for stock or custom positions, different swingarms, width etc and has drill guide and location pin attachments .
Also good for checking the stock shock mount positions which are hardly ever exact.

Thanks zed - looks like that would make things a lot easier. Any chance you could post a few more photos? I can see what looks like two adjustment screws but I'm not sure how everything fits together (how the two sides are kept aligned, how the shock length is locked into place...).

Took some measurments today.
The GSX-R swingarm has the same spacing from the pivot bolt to the lower shock mounts as the stock swingarm. The axle is 30mm further down and 55mm further back with respect to the bottom shock mount. The new shocks are 20mm longer.
I'll wait until the rims get here but the plan at the moment is to move the top shock mounts to the same location as the Z1000J. After that I'll see if I need to drop the top yoke down or not.

Put a few things together today so I can see how the riding position is when the footrests get here. Would be interested in opinions on whether I should go with scantily clad or fully naked:

 

 

 

 

 

wrote:

DoctoRot post=845781The KZ650 has great stock geometry i wouldn't stray too far from it, unless your are doing the complete package.


What do you mean by "doing the complete package"?   

Comparing the stock 650 to the 900 for discussion purposes.

Rake 27 deg vs 26 deg
Trail 108 mm vs 90 mm.

I have both triple trees but wanted to use the Z1 because I have pretty much an entire front end that I could use.  If I go back to stock 650 I need to buy the front end...forks, gauges, gauge mount, brakes, etc.

 

Complete package would be changing fork offset, wheel size, forks, rake, wheelbase, swingarm angle, shock angle, ride height, etc...it all adds up

I'm not very familiar with the Z1 stuff but IIRC they use 36mm forks so that will fit the KZ650 triples so you can use the forks, wheel, and brakes. The only things that wouldn't fit are the gauges. You could have the Z1 gauge mounts welded on the KZ triple. Or you could just try the z1 triples out since you already have the parts in hand. 90mm is very little trail by modern standards, probably why the z1s were prone to tank slappers. What is the fork offset on both the triples? you can easily do a little calculation to see if its going to the realm of unsafe.

A bit more work done today. Chopped a few unnecessary things of the frame (rusted out pillion footpeg brackets, brake lever brackets seat brackets.

   

 


One of the seat hinges had already been removed - someone was pretty heavy handed with the grinder.

 


Got the GSX-R swingarm and the forks on.

 

 


Checked the axle height against the stock setup. Ground clearance was 130mm/145mm (front/rear) on the stock setup, putting the frame pretty much level when the wheels are on. New clearance is 145mm/80mm. This reduces rake a bit (the two photos below show the difference between stock rake and the new rake (I propped up the swingarm until both axles were at the same height). I can drop the forks down about another 10-20mm, but the major difference is the swingarm and shock length (both are a bit longer than stock). I can shorten the shocks by about 8mm but there isn't much else I can do at the back short of moving the shock mounts.
I realise that the rake will change due to tire profile and sag, the idea here was to get a comparison to the stock setup, not to actually figure out the exact numbers.
I would appreciate some opinions on how this will ride. Do I need to mess around with things, or do I just see how it goes and get a stepped top yoke if it doesn't feel right?

EDIT: Just did some maths and the rake will be reduced by about 3°, so should be about 23°. 

 

 

Getting back into things again. Put the stock forks and swingarm on today to check th height. Raised the frame of the floor and measured from the floor to the centre of the wheel axles. Will make it easier to check if the nose is dipped with the new triples and ZRX forks. One problem though: the shocks that were on the bike don't look stock. Can anybody tell me the length of the stock shocks on the KZ1000A1? Just want to make sure my starting point for the frame angle is stock.
The modified GSX-R swingarm and Öhlins shocks arrived yesterday. I'll be chopping a few things off the frame tomorrow so I can get the swingarm mounted (brake pedal bracket needs to go). Once that's done I can get the ZRX forks back in and check the height of the front and back axles. If I'm lucky the bike will be level at the middle of the height adjustment range on the shocks.

 

Lots of upgrades occur after as a result of failures during initial bike runs.  Heads were prone to leaking oil on Z1's with single gasket.  Later models had a two piece gasket and an O ring.  Kawasaki eventually went to needle bearings in the swingarm but I bet a lot of people converted their bikes long before the factory did.  O ring chains are an other improvement over the old oil systems.

Some others off the top of my head...sealed batteries vs open cell, wheel balance weights glued to the rim vs lead weight on the spokes, etc.

I am a big fan of your build! I am doing a very similar build on a 76KZ900 LTD. I am curious as to what rear wheel, hub and brake set up you went with. I am also using the same GS1100E swing arm. Thank you for any help that you can provide me.

The worst wobbles I had was in the 70's with the bike naked in stock trim. The Z1's were well known to have high speed wobbles due to weak frames and swing arms. The brace under the steering head always had cracks in the same spots at the cooler bolt holes. There was a cheesy fix for that I figured to be just plain stupid. A small bolt on bracket.   They were offering new bronze swing arm bushings and if you REALLY wanted to be cool you could install a needle bearing kit for $250. Should have been there anyway.   First thing I did was to beef up the steering head bracket covering the cracks, gusset the backbones and installed the new bushings  It was better but it was still prone to wobbles. With the new KZ's they quietly beefed up the frames and added a gusset under the steering head the Z1's didn't have and went on to business as usual. It's obvious they knew of the problems but decided to ignore it. Early KZP's brought the issues to light but they did as little as possible, they just redesigned the swing arms along with a few other things. To this day aftermarket has been addressing these issues with gusset kits, custom swing arms, etc. The biggest improvement is the late model KZP swing arm that is 1 1/2" longer and modern pivot bearings. It now shows how weak the front end is. That I'll be addressing next.
Steve