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TOPIC: Bar end weights

Bar end weights 02 Feb 2019 07:22 #798057

  • Olajoe
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On all of my kawasakis that I own right now including my KZ1000 that i've owned since early on, all in my garage, not made up (FAKE POSTING i think). My bikes that came oem with end weights have them, those that didn't don't.
ZX12R
1981 KZ1000CSR-M

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Last edit: by Olajoe.

Bar end weights 02 Feb 2019 16:12 #798082

  • loudhvx
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riturbo wrote:

loudhvx wrote:

SWest wrote:

loudhvx wrote: When properly weighted, they can reduce vibration in the bars, but there is a potential downside. If your bike is prone to tank-slapper, the bar-end weights can increase the likelihood of it happening. Most Kz's are pretty stable, but the early standard 550's seem to like to oscillate more than others, and they can go into a bad tank-slapper at high speeds, especially the 81 Gpz550. (Kawasaki redesigned the geometry for 1982.) One way to avoid it is to reduce the steering inertia by taking weight off. This increases the resonance frequency to a speed you hopefully can't attain with the bike. Adding weights at the ends of the bars would be counter to that strategy.


I didn't think about the tank slapper hazard. Haven't noticed a problem.
Steve

Yep... learned the hard way... exited the vehicle in deep triple digits.



Same thing happened to my brother on his 81 . Went down on highway doing a 100 plus . Its my bike now . Never had it happen when ive been on it . So whats the best fix for this .


After my crash I decided to research the problem, but this was before the internet. I bought race-bike construction books which covered the subject. Through many laps of testing they discovered the high-speed wobble was related to several things, but most significant was the rear tire. The best corrective measure is to make sure the back tire is not too wide for the rim, and not worn down to being squared off. I believe that was a major contributor to my crash. After replacing the rear tire, the tank-slapper did not come back even at higher speeds.

On top of that, make sure all of the bearings and other chassis parts are in good working order and the frame is in good alignment. This should go without saying.

But even with all of that, you might have to go further. They mentioned that the geometry of quick-steering race-bikes (like the 81 Gpz550) is a factor which is not easily altered, but you can do some things to make sure you don't make things worse. For one, don't raise the back end of the bike too much without evening out the front. Doing so reduces the steering angle, making it more vertical and thus "quicker". Likewise, don't lower the front end a lot either without evening out the back. There are a few other precautions you can take. As I mentioned, they recommend lightening up the steering... forks, wheel, bars, headlight, etc... anything that turns with the bars. The idea is that the resonance frequency, by reducing the inertia, will be at such a high frequency, you will hopefully never be able to attain the speed necessary to generate a tank-slapper.

You can also add a forkbrace and a steering damper, but those devices are not for the purpose eliminating tank-slapper. They are for reducing another phenomenon of light, quick-steering bikes, and that is headshake. Headshake is a brief, single twitch of the bars due to irregularities in the pavement and is often worse when under hard acceleration. This is not really for tank-slapper, but might help reduce the intensity of a tank-slapper. I won't ride a Kz550A (standard) or Kz550D (gpz) fast without a steering damper. It's so much more stable when going over bumps, tracks, and pavement joints at high speed.

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Bar end weights 03 Feb 2019 06:19 #798106

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Thanks loud Great explanation . Dont want to keep hijacking this thread but if you get a chance could you post a pic of your damper . Have a fork brace on the bike already . Thanks again
derrek
Gpz 750 turbo The one I ride
Gpz 750 turbo Not finished
Gpz 750 turbo Not started
Gpz 550 1981
Gpz 550 1983
Bunch of other junk

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Bar end weights 03 Feb 2019 13:37 #798137

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riturbo wrote: Thanks loud Great explanation . Dont want to keep hijacking this thread but if you get a chance could you post a pic of your damper . Have a fork brace on the bike already . Thanks again
derrek

I'll start a new thread when I get some decent photos.
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Bar end weights 11 Feb 2019 16:39 #798503

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Bar end weights 12 Feb 2019 10:24 #798545

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Ive no problem with you hijacking the thread and taking it where you want, I got what I needed from it. thanks for the replies.
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