Z1 Stability Issues

[ROZZER]

OK I know Z1's arn't exactly known for great handling /stability but mine is absolutely crap!
Z1B fully restored, new pattern shocks (not brilliant I know), new taper head bearings (correctly adjusted), new swing arm bearings with pivot correctly torqued, frame is straight (it was bent @ headstock but had it straightened on jig 7 yrs ago - Seastar Superbikes in Norwich if anyone is interested).
The issue is stability, the bike tracks every rut/imperfection in the road and when crossing white lines/cats eyes, the back end shimmies/wobbles and generally feels loose. Over 100mph (on private roads of course!) and higher speed corners a weave sets up, this is affected by clothing, in leathers its better, in fabric jacket worse , body position also affects the weave severity.
Tyres are Continental ATTACKs (not latest version) with good tread and profile, pressures 28 front, 32 back, I use Kawasaki owners manual figures but should they be different based on tyre manufacturer as most modern bike tyres run much higher pressures?

Cheers

John
I suspect its the tyres, the bikes were alledgedly fitted new with ribbed front tyres for straight line stability but with modern tyres this shouldn't be an issue.
Anyone have any suggestions / recommendations for tyres (from experience).

[wilsonsjw11]

John,
I would suspect the tyre pressures are too low.
I have Battleaxe fitted to my Z1s and run 36lb front and 37lb rear.
Regards
Steve

[Pigford]

Tyres would also be my first bet Pressures make a difference (as stated above) but not always a 100% cure.

Even my modern W650 was tracking & shaking its head with a half worn Accolade tyre up front - now has new TT100's and it transformed the bike

[mick znone]

ive been using my bike of late, it hadnt been ridden much since new tyres a few months back, it was weaving and wobbling, i checked the tyres and the rear was very spongy, i must get the pump on it good thing about this cure is its free.

[Garry.L]

http://www.youtube.com/watch?v=fvsDIq3WwVA

[Al]

John you might get something by having a read of this.

http://www.z1ownersclub.co.uk/forum/vie ... c&start=15

I have Conti Attack CR2's with 29 front and 35 or 36 psi rear. (these are radials!!!!!)
If you want to change tyres how about newer versions of what you have if you are happy with them as they stand.

A fork brace would probably help but probably not so good on a standard looking bike.
Overall, it is probably a combination of a number of things.
Too soft springs on the front, too thin oil in the front (too little damping), incorrect weight balance front to rear, excessive (involuntary) rider inputs from handlebars.

You could try as a test; 35 PSI in the rear, drop the forks through the yolks 1/2 inch, thicker oil in the front, lower or narrower bars, a higher damper setting on the back if they are adjustable. If these help at all, work toward those that are acceptable changes that you can live with.

Pressing down on the back end a few times when static should show a distinct reluctance to return to the top of the stroke if there is sufficient damping in the rear shocks.
Try it cold and hot and see what the shift is between the two conditions.
If its noticeably less damped when hot, then shocks are not up to the job they are being asked to do.
AL

[mick znone]

http://www.youtube.com/watch?v=fvsDIq3WwVA

really useful video that Gary

[njwmct]

Modern tyres will be designed to run at higher pressures than those tyres which were available when your bike was designed - so the original pressures recommended by Kawasaki are probably too low.
Look up the tyre manufacturers recommended pressures for your particular bike.

[KeithZ1R]

Always had the same effect using Metzlers as well. shimmy on over banding and white lines palpable weave on fast bends, just took the hint and slowed down until it stopped. I think body weight plays a large part in it all as well, just my tuppence worth

[jimmock]

These DO make a difference.

http://www.ebay.co.uk/itm/ADIE-BIKE-STA ... 2c707c0b6b

[chrisNI]

These DO make a difference.

http://www.ebay.co.uk/itm/ADIE-BIKE-STA ... 2c707c0b6b

Those just stop you actually falling over they don't stop you weaving all over the place...

[PAULJAC47]

You are right about the repro shocks they truly are shocking might be worth fitting some Hagons or similar,i find rubber choice is important as is pressure of the tyres your weight is also a factor.Battlax and Roadriders tend to be good choices....

[mick znone]

checked my rear tyre today, it was 11 lbs pressure, im not surprised it was weaving thats on a knobbly tyre too
i stuck those repo shocks on my z1a and it weaved allover the place.