mach111
Novice Class
Posts: 81
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posted October 04, 2002 12:24 AM
handlebar shake?
anybody know if going from a 120/70 to a 120/65 front tire will make the handlebars shake left to right?.My bike has never had a problem with this matter even with the tires not being properly balanced before.But i cannot figure out if its a defective tire. i wanted to put a 120/70 on,but only had access to a 65 series.both front and rear are pilot sports.190 on back. i know its something with the front tire because as soon as i put the front tire on & balanced it, this started. only if i let go of the steering wheel at 30-50 m.p.h the handlebars sway left to right.fast,but not far,just a quick left to right shake.
I'm almost sure the tire does not bounce or shake at higher speeds,well i cant say for sure cuz it only shakes when i let go & i'm not gonna let go of the bars after 60 m.p.h.what do you fella's think?tire balance,bad tire,bent something?most friends have said balance but,there has been times in the past i lost a weight on the tire and the bike still did not shake at all.but again it only does it at about 30-50 m.p.h.? someone told me since i went to a 120/65 the lower profile tire can do this.should i rebalance a properly balanced tire,or replace it?if something was damaged upon install, wouldnt it do it all the time?i cannot figure this one out cuz my bike,even lowered always was real good about no shakes and going in a straight line down the road.any input here would be appreciated.
  
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slug
Pro
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posted October 04, 2002 03:03 AM
on my bike(yzf600r) a d207 uo front causes handlebar wobble. in stock sizes.
no other tire that i have tried does this at all, so i ruled out rim, balancing (since balanced the same on all of them) and other mechanical problems. i think mine was just the combo of tread pattern and tire shape.
pilot sports, the bt57 plastic that came on it, and the m1 tires don't exhibit this problem.
you may be able to adjust a little on the suspension to fix it.
hope this helps out
   
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dougmeyer
Needs a job
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posted October 04, 2002 07:11 AM
It's not "wrong". It just "is".
Don't take your hands off the bars. Seriously- YOU are the steering damper.
Note that if you so much as lay a finger on the bars, it stops. The tire combination you have has altered the natural oscillation frequency of the front end. There are tire combinations on MANY bikes that exhibit this phenomenon. Live with it or change the combination.
Doug
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brickman
Expert Class
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posted October 04, 2002 08:58 AM
my bike do's the same thing with a 70 on it.
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mach111
Novice Class
Posts: 81
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posted October 04, 2002 08:32 PM
well it was the 65 series tire,the balance today checked out o.k. just to be sure,i put my friends 70 series back on and all shakes were gone.cant live with that shake for 5k miles,maybe if it was a back tire.so i would not recomend going to a 65 series with a 190 rear.i cant believe that difference in tire size made that much of a shake.learn something new everyday on the almighty z!
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ZHooligan
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posted October 04, 2002 10:03 PM
I would assume the profile on the 65 is lower then the 70. That would drop the nose some similar to pushing the forks up in the triple clamp. And as we all know that eventually leads to head shake. And if I remember I think I also read the 190 is taller then the 200 which would also steepen the rake and make the bike turn quicker but again contribute to headshake.
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mach111
Novice Class
Posts: 81
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posted October 05, 2002 09:51 PM
good point zoo.i guess a stabilizer is on my list of neverending mods for the z.
i was gonna stop the mods after the pipe and minor look changes,but it never ends,seems there is always something to buy.the dunlop's are great so far,no shake.
now when i say no shake i mean within reason, we all know only a stabilizer will keep your handlebars "shake free".but it was a big difference.i guess its something i have to live with.i cant even run lighter bar ends.sometimes i put em on for a different look except on a long weekend ride. how much & who has good prices on stab's?
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ZHooligan
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posted October 05, 2002 10:05 PM
 Edited By: ZHooligan on 5 Oct 2002 23:35
Well your options are the Muzzy damper and the Scott. Both a good. And there have been a zillion posts about both. You will be spending a little over $500 or so on either of them. I like the Scott but the real issue is get one or the other. One of the guys (Turboblew) is advertising a used Muzzy in the classifieds for $425. Sounds like a pretty good price.
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mach111
Novice Class
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posted October 06, 2002 08:38 PM
do they work well on the z,i never had a need for one till now?
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ZHooligan
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posted October 06, 2002 11:15 PM
Since putting one on my 12 I have almost zero headshake. The tiny bit I have experienced was minimal, it came on the race track at the exit of a really high speed turn where you hit a bump on the exit just as you straighten the bike up and are really hard on the gas. The bike without the damper would pitch you off with it it is a minor twitch. Good insurance in my book.
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mach111
Novice Class
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posted October 07, 2002 01:12 AM
maybe i'll leave santa a fifth of j.d this year instead of some shitty cookies!
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TurboBlew
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posted October 07, 2002 04:16 AM
Mach, I had the BTO 120/60 on my bike once. Made me feel like I was riding an R1. (twitchy as hell) My 120/70 was doing that to, but then I increased the tire pressure from 32lbs to 38lbs and it went away.
Check your tire pressure! I like the 70 profile tire anyway. The bike is easier to predict. The 60 profile falls in too quick. Now on the OH2s, the 60 profile would be suicide! ITs twitchy enough with the 70 profile!
Im gonna take the suspension apart this week and make sure everything is lubed and working correctly.
The tire pressure on my 208s were alittle low for my tastes. I had to put 5lbs in the front and 7 in the rear!
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FinalVelocity
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posted October 07, 2002 08:32 AM
Edited By: FinalVelocity on 7 Oct 2002 09:55
Here we're back to this damn handlebar shake problem. Good.
I've still got bad handlebar shake when I take my hands off the handlebars at
40-55 mph. Went to three dealers - none can fix the problem, and all ended up telling me it's 'normal'. Can't be normal!
Had the head bearings looked at, one dlr said they're ok. Checked wheel alignment, balance...they're all fine. Front tire was slightly cupped - replaced it with a new Pilot. Redialed the suspension to my body weight and riding style (I'm at 4 clicks towards a harder setting from the factory setting. Spent a couple of hundred bucks (in these troubled economic times) with the 3 dlr visits and a tire change and I'm still back with the violent handlebar shake.
I'm running the same Mich. Pilots, except they're stock size.
Kawasaki told me that I should'nt let go of my hands off the handlebars even to test for the shake. What a load of crap. And the shake does not go when I hold the bars lightly with a touch either, so it's gotta be something.
Wilson's ridden my bike (before his accident), and he also noticed that the handlebar shake was SO bad it almost threw him off.
Only thing I can think of is to go back to Dunlops, maybe it's just the Pilot Sports that's causing this? Hate to throw more $$$ without knowing if it's gonna solve the problem.
A steering damper would only hide a potential problem.
Any input is appreciated.
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ZHooligan
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posted October 07, 2002 05:55 PM
I doubt the dealer really checked things, but....
I would loosen the bottom triple clamp bolts and collapse the front forks as severly as possible. i.e. push the bike and slam the front brake on and load the bars to colapse the forks. The forks in the clapsed state become very ridgid and if they a twisted out of alignment this will usually straighten them up. Then I would still put the bike up on a front stand (using the steering neck to pick the bike) loosen the axle pinch bolts and spin the wheel and slam the fron brake again a few times this also helps to align things. Then retighten your triple clamps. Carefully check to make sure the forks are in fact the same height in the triple clamps and then the front axle pinch bolts, Then the last but not least or do it first have the front wheel rebalanced to insure it is balance.
This has solved my problems like yours everytime. With the exception of once and it was a Michelin Piolot front tire that was indeed cupped and I put a new tire on and the issue was over.
If that doesn't solve things I can only asume it is a wheel issue. The other thing you might try if you have a friend with a 12 is put his front wheel on as a check.
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aliveagain
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posted October 07, 2002 06:19 PM
You may want to check the rest of your bike for loose mounts or rear wheel,oscilations can come from differant locations.About your rims,coming down hard from a wheelie or hitting a nice road dibbit can put a flat spot on the rim.
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FinalVelocity
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posted October 08, 2002 05:40 AM
ZH - actually Wilson and I performed the exact procedure. No use.
Aliveagain - I don't do wheelies.
Any chance wheel bearings could go bad?
Damn wish I found the cause of this problem. 
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ZHooligan
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posted October 08, 2002 07:39 AM
Wheel bearings can go bad. Pretty rare on a modern day street bike. The steering head bearings are more likely.
Have you been able to swap front wheels with someone to check that out?
The only onter thought I have on this (assuming the bike has not been wrecked and something bent that has not been discovered) is the actual chasis setup. Anything that you have done that effectively drops the nose or raises the rear can make the thing shake. If you have really stiffened the rear end for example that races it and will make the bike turn faster and can create head shake problems. Or if you have done something to the forks. I have seen where the rebound damping is turned in or up to the point that the suspension starts packing which again changes the steering geometry and will cause head shake. You might want to back off on your clickers.The packing part I am talking about if you don't know what it is is where the suspension collapses or absorbs the bumps and the rebound dampinh doesn't let the suspension come back fast enough so the cummulive number of bumps slowly collapses the suspension. I have seen both Street Bikes, Road Race bikes and Mortor Cross bikes that are set up wrong come in from a ride and they look like one of those low rider rigs where the hydraulics lift the car. The bike setting there by itself slowly gets back to a neutral position. Don't know if this is an issue for you but it is worth a shot.
It maybe that your bike just likes Dunlops, but then so do I!!!
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FinalVelocity
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posted October 08, 2002 12:38 PM
ZH my 12's clickers are not too turned in - just set up a little harder than stock. I can check them and report. No I haven't swapped wheels with anyone. I need to try that.........
I should try that. Or maybe it just hates Pilots!
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aliveagain
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posted October 08, 2002 05:04 PM
The book that kawasaki handed out mentioned how they tried different tires,and that when they went to a wider fork pitch for better steering feedback, the tires no longer worked.they caution owners about changing tires for performance reasons.you already know that the 120/70 works,why not cut your losses and go back to the originals?
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FinalVelocity
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posted October 09, 2002 09:12 AM
I am on 120/70. Just replaced the D207s with Pilot Sports.
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Zhooligan
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posted October 09, 2002 01:15 PM
Are you going to be able to hook up with another 12 owner and swap front wheels for a check?
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FinalVelocity
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posted October 10, 2002 05:54 AM
I dunno. Need to get a hold of some Detroit Area riders. But this problem I have to solve!
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EastBayDave
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posted October 10, 2002 06:11 AM
read my lips: Muzzy Dampener Muzzy Dampener Muzzy Dampener Muzzy Dampener Muzzy Dampener 
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ZHooligan
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posted October 10, 2002 07:37 AM
Eastbay.... The dampner is a must have in my book. But, it isn't right or normal for the bike to do what FinalVelocity is describing. So he needs to solve the problem. In my opinion, a damper in this case would be the same as using stop leak to fix the radiator as a permanent fix.
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future; -- Youth is forever.
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FinalVelocity
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posted October 10, 2002 01:47 PM
Edited By: FinalVelocity on 10 Oct 2002 14:48
When I first had the bike with orig. tires - there was no shake. It's just slowly developed I guess. IMO my 12 does'nt need a damper....well maybe if you could afford one it's good to have it. Before the handlebar shake developed my 12 was stable even at speeds upto 180-190 indicated. I could take my hands off the bars at 100+ and it was rock steady. Then this crappy problem started sometime.
I don't want to install a damper and mask what is a potentially serious problem.
Maybe after I fix this shake....but even then $600 for a steering damper is too rich for my blood.
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