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KZ1000 wheel sizes and frame geometry?

  • DoctoRot
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29 Jun 2011 02:48 #460080 by DoctoRot
KZ1000 wheel sizes and frame geometry? was created by DoctoRot
So I have been doing some minor upgrades to my 78 KZ1000 LTD. One of them was getting a GS1100 swingarm so i could run a wider rear tire. I am going to re-lace my wheels, and want to get wider/bigger rims, mostly for cosmetics, but also to get a larger contact patch. Ideally I'd like a 18x2.15" in the front and a 18x3.5" in the rear. My concern is that by doing this i will be changing the geometry of the bike which could make it unstable. I'm willing to entertain different rim size combos, such as maybe a 19x2.15 in the front instead.

Someone told me that if I start changing the frame geometry I should get a steering damper to prevent a tank slapper. I experienced one on the freeway before and about messed my pants, I really really don't want to go through that again. Any thoughts on this is much appreciated.

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  • TeK9iNe
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29 Jun 2011 11:02 #460114 by TeK9iNe
Replied by TeK9iNe on topic KZ1000 wheel sizes and frame geometry?
Going bigger on the tires and such isnt too bad. Frame changes and additions/subtractions are another story...

If you're really scared about it, increase your rake (if possible) and add leading axle forks.
You shouldnt have any problems after that.

B)

Motorcycle Shop Owner/Operator

79 Kawie Z1000 LTD
81 Kawie Z1000 CSR
83 Honda VT750C A
85 Kawie GPZ900 A2
86 Zukie GS1150 EG
93 Yamie XV1100 E
Lucky to have rolled many old bikes through my doors ;)

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29 Jun 2011 17:57 #460173 by dutchz
Replied by dutchz on topic KZ1000 wheel sizes and frame geometry?
I would not be too nervous with the modifications you are making. The 18" front wheel will make it steer a bit quicker and the longer swingarm will increase straightline stability so that should make for some pretty neutral handling. You could install a steering damper as a precaution. I have the same wheel sizes with a stock arm and much more extreme geometry and my bike is rock solid on the freeway. If you want to experiment a bit you can drop the forks through the trees 0.5" to emulate an 18" wheel and see how that feels for you.

1974 Kawasaki Z1
Stock front hub and rear axle.

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29 Jun 2011 18:32 - 29 Jun 2011 18:33 #460174 by OnkelB
Replied by OnkelB on topic KZ1000 wheel sizes and frame geometry?
Like Sander says, it shouldn't be a problem.

I'm running 18" PVM wheels front and rear on my GPz 1100, front is a 2.5" with a 110/80/18, rear is a 4" with a 170/60/18, both Metzelers. Also a K&J (Krüger und Junginger) swingarm, Koni rear shocks and stock GPz front end.

The bike handles really well, never had even the slightest hint of a wobble and I have been over an indicated 120 mph on a couple of occasions.

As for steering dampers, personally I don't care much for them - my thought is that if you need one, you have a problem somewhere you need to address rather than mask it, but that's just me.

77 KZ 650 B1, 82 GPz 1100 B2.
Last edit: 29 Jun 2011 18:33 by OnkelB.

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  • wireman
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04 Jul 2011 02:16 #460881 by wireman
Replied by wireman on topic KZ1000 wheel sizes and frame geometry?
the 18" front wheel will probably be easier to find decent tires for than the 19".
kawasaki switched from a 19" front wheel to an 18" on the 79 z1r if i remember right and had serious handling issues,of course they also had a fairing bolted to the forks also which could of been a lot of the problem.
as long as the bike sits level,not lower in the front than the back i would think youll be fine since that wont really change the geomotry of the suspension.
its when you dump the front of bike into the weeds to quicken the steering radically that ive had first hand experiance with a tank slapper,and its no fun im here to tell ya B)

posting from deep under a non-descript barn in an undisclosed location southwest of Omaha.

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  • KZQ
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04 Jul 2011 03:05 #460889 by KZQ
Replied by KZQ on topic KZ1000 wheel sizes and frame geometry?
"...im here to tell ya"

I'm glad for that!

Bill

www.KZ1300.com
Riders:
1968 BSA 441 Shooting Star, 1970 BSA 650 Lightning, 1974 W3, 1976 KZ900, 1979 KZ750 Twin, 1979 KZ750 Twin Trike, 1981 KZ1300, 1982 KZ1100 Spectre, 2000 Valkyrie, 2009 Yamaha Roadliner S. 1983 GL 1100
Projects:
1985 ZN1300

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  • wireman
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04 Jul 2011 03:20 #460891 by wireman
Replied by wireman on topic KZ1000 wheel sizes and frame geometry?
closed my eyes held on really tight and stayed off the brakes,no skill what so ever involved in saving that one.
i do remember thinking about how deep the misouri river was and wondering how it was going to feel clearing the bridge at 90 and landing in it though! :sick: :woohoo:

posting from deep under a non-descript barn in an undisclosed location southwest of Omaha.

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04 Jul 2011 11:45 #460923 by donthekawguy
Replied by donthekawguy on topic KZ1000 wheel sizes and frame geometry?
I have a GS arm and an 18 inch wheel on the front of mine. Handles a lot better now.

Rathdrum Idaho
1971 Kawasaki g3ss
1972 Yamaha R5 350
1965 Suzuki Hillbilly
1964 Yamaha 125

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20 Jan 2022 08:37 #860779 by Samminorwich
Replied by Samminorwich on topic KZ1000 wheel sizes and frame geometry?
Could I ask if you haven't started to pull the rear apart could you measure the rear wheel offset to help me build my spoke wheelRe

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20 Jan 2022 14:54 #860798 by 750 R1
Replied by 750 R1 on topic KZ1000 wheel sizes and frame geometry?

Could I ask if you haven't started to pull the rear apart could you measure the rear wheel offset to help me build my spoke wheelRe

This thread hasn't been replied to since 2011.   You still haven't explained what you are referring to as "offset".
A quick search turned up this Z1000A rear rim lacing tutorial...

z900collector.wordpress.com/restoration/...ing-z1000a1-z1000a2/
The following user(s) said Thank You: kzstreetfighter71, DOHC, Mikaw

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20 Jan 2022 18:23 #860807 by Mikaw
Replied by Mikaw on topic KZ1000 wheel sizes and frame geometry?
750R1, nice article. Thanks for finding that. 

1976 KZ 900 A4 kzrider.com/forum/11-projects/613548-1976-kz-900-a4
1976 KZ 900 B1 LTD
1978 KZ 1000 B2 LTD
1980 KZ 750 E1
Kowledge Speaks, But Wisdom Listens.
Jimi Hendrix.

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21 Jan 2022 01:39 #860811 by 750 R1
Replied by 750 R1 on topic KZ1000 wheel sizes and frame geometry?

750R1, nice article. Thanks for finding that. 
Hey mate, no worries.   I'm still trying to work out what Samantha is talking about, she's rather cryptic..!!
The following user(s) said Thank You: kzstreetfighter71

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