fly zx12
Novice Class
Posts: 38
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posted March 31, 2003 02:43 PM
shaky front end
After I had new tires installed, when I got up to approx. 80mph the front end began to shake. I checked air pressure, tire alignment, spacer gap on the right fork and re-torqued everything to spec. Any suggestions would be greatly appreciated. I am begining to think I should do my own maintenance.
  
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jonwright
Needs a job
Posts: 2416
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posted March 31, 2003 03:42 PM
Different tires? Sometimes differing tires have different circumferences that can throw off the geometry of the bike requiring lowering or raising of the forks or rear end. Same sizes? Sure the tire is balanced?
Of course, don't ask me for any practical advice - I just know theory. 
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TedG
Moderator
Posts: 8222
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posted March 31, 2003 04:27 PM
Check to see if the bead really seated. There is a molded in line that should be pretty even all the way around. Balance can do the same thing.
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Ted
2000 Green ZX12 sold
The fast color!!
Green 2005 ZX10R
2009 Concours Black ABS
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fish_antlers
Administrator
The Truth is Out There
Posts: 21894
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posted March 31, 2003 04:43 PM
what kinda tires/ brand?
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FLY ZX12
Novice Class
Posts: 38
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posted April 01, 2003 06:08 AM
I switched from Dunlop 208s to Bridgestones BT012SS. I checked the front this morning with the front end up and noticed that while rotating the tire that it seemed to stick a little in the same place everytime. I am thinking that when they changed the tire they could have hit the front rotors and slightly bent them. With that I would think that could let it ride somewhat smooth until about 80. Maybe I am thinking to much, but let me know what you think of that? Thanks again for your inputs.
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r21xz
Expert Class
Posts: 109
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posted April 01, 2003 10:44 AM
My 12 did'nt shake with bad rotors. I'd say it's the tire causing the prob.
A friend of mine,a while back,had a shake at around 100mph. We came home,balanced the frt tire,and it was fine. It was an Avon,and took alot of weight to balance it. I believe they have to be WAY out of balance to get the shakes?
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Koz
Expert Class
Posts: 304
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posted April 01, 2003 12:10 PM
Re-balance the tire!
Koz
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FLY ZX12
Novice Class
Posts: 38
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posted April 03, 2003 11:56 AM
I took the bike back to the shop I had put the tires on. I told the mechanic that I thought it might be the rotors. Anyway I called today and they were bent or warped as he put it. I guess I will find out soon if that really is the cause.
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redelk
Moderator
Please... speak to the hand.
Posts: 3212
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posted April 03, 2003 05:49 PM
Having warped a set of front rotors on both a 7R and a 12R (I'm a wuss and brake a lot), I can attest that warped rotors, by themselves, would not cause a head shake. When braking, they would cause an almost "up & down" oscillating feeling in the bars, but normally not a "left & right" shake or shimmy. Also, if the brakes were not applied, I would not feel any form or type of vibration. Not at any speed.
My last set of rotors were over FOUR TIMES past spec. tolerance. Still no shake. Me thinks the problem is elsewhere. Just IMHO.
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There are only three sports: bullfighting, motor racing, and mountaineering; all the rest are merely games.
-Ernest Hemingway
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