750 R1 wrote: Did you use all the GPZ linkages and mount them exactly the same..? If you've changed the length or position of those linkages, or the shock, then the suspension will have different geometry, small changes can have a big effect, Look up the GPZ900R and see how much travel the suspension is supposed to have, also take into account your 1100 is probably a lot heavier than the 900...

100% agree with that!

I recently worked on a mono shock on a project that had been started but not really tested or finished complete…Unless it is EXACTLY set uo like it was from the bike it was taken from expect do play around A LOT with spring rates .
Is it a progressive rate linage or straight rate? it looks progressive but measuring is the only way to know if it is and how progressive it is.
You may need measured the distance of swing arm travel vrs shock travel in 10mm increments or less to determine this. This requires removing the spring and finding a way to move the swing arm and measure the shock travel vrs swing arm travel,
Also have you set the static sag and do you know how much shock travel you have? This will help determine where the problem is, to try to find out if the spring is to stiff or the linkage rate is to high or low if its progressive,

Custom mono set ups can be a challenge , I am still messing with that project, I only went through 5 springs to find on that would be close :blink:

Looks like a really cool bike, don't give up!!!

ZX9R front on mine,GSXR600 swingarm and Bandit 600 wheel on the rear.

great site, cant believe i just now found it, im building my 3rd kz1000 and really like the look of some of the bikes on youtube and the front end and rear tire and swing arm are definitly not stock, what bike front end are guys using, looks like a gsxr on some? appreciate any help someone can share that has done this. i wanna keep my triple tree or does that have to go too?

Nessism wrote: WOW! Those S1 swingarms are impossibly cool! Wish I could ride hard enough to out handle my stock swingarm because if I could I'd have me one of those things!

Just let the swingarm bearings dry out and fail, then just pretend its your sublime skills that are making the bike buck and weave, buy new swingarm....Problem solved... :woohoo:

I'd love one too, my wallet says otherwise....

WOW! Those S1 swingarms are impossibly cool! Wish I could ride hard enough to out handle my stock swingarm because if I could I'd have me one of those things!

Hey Steve, I am doin fine mate -
How are you ?
BK - it is 450 mm from centre of swing arm pivot to centre of shock mount.

OutlawShank wrote: Thanks, how do you suggest lowering the rear?

Shorter shocks is the easiest route. You should remove the shock springs (Google shock spring removal zip tie), install the shocks and actuate the swingarm to look for any contact with the fender/chain, etc. If the tire hits the fender you need to install a longer shock bumper or shorten the shaft.

Hi Kats,

Can you post a few pics of your bike? A few areas you want to check are, the swingarm pivot bushing, wheel bearings, steering head bearings, brake caliper pistons, master cylinders and for sure flush out that fork oil. One thing I always do before tearing down any engine is check all my valve clearances and write them down for reference, keep a log book specific to that bike. When reinstalling cams be sure not to get mixed up with your ignition rotor marks as their is a 1/4 TDC and another mark to the left for your ignition. I always turn the engine over by hand using the large nut on the end of the crankshaft @ 6 times or so with the plugs out to make sure valve assembly does not bind or get familiar with the pistons... just to make sure.

Doug

To the OP, I would be checking steering head bearings, wheel bearings, both front and back, and swingarm bearings, all of these things can lead to a high speed weave or wobble, I doubt it is a tire out of balance thats causing problems over 90MPH, also make sure your tires are seated properly and as mentioned, make sure the valve mark on the tire is lined up. I've seen plenty of poorly seated tires , although they usually lead to a up and down type of wobble, if that makes sense...

Kidkawie wrote:

I_Tig_in_piece wrote:

650ed wrote: If you had a 72 mph speed wobble something is still wrong with the bike and the damper is only masking the problem. I guarantee you that the bike didn't have a speed wobble when it left the showroom floor. #1 suspect would be tires, but bad shocks; worn swing arm bushings; bad steering stem bearings; wheel bearings; untrue rim; etc. are also possibilities. I highly recommend you identify and correct the problem. My KZ650 had a wobble at 90 mph and after replacing all bearings, bushings, shocks, etc. it turned out to be a bad tire (Michelin Macadam) even though both tires looked perfect. After replacing the tires the bike is now as solid as a rock up to top speed (120 mph). Ed

Before the first wobble, all the items you mentioned had maybe 400 miles on them from new. AB bearings everywhere except the swinger which is a NOS set. I trued the wheels myself then had them OK'd by a few buddies at Trophys. Followed the directions on kz400.com to the T to rebuild and fill the forks. I pressed the new top and bottom AB races on but I didn't re-torque the stem after putting some miles on them.

My Z1B with stock forks and reproduction OEM shocks would weave above 80mph. Not headshake, but a whole bike weave. I installed a set of ZRX shocks which were plusher and a touch longer and the weave has disappeared. With these old bikes you have to pay attention to setup. You can't just slap suspension on (no matter what it is) and call it done. Some good info in this video.

That video played like an anti motorcycle propaganda piece.
I've never had any of my medium and big road bikes do any of that BS!
And I ride from 55mph to 85mph for quite a few miles nearly every time I go out .
Today included.