GS1100E High Speed instability

[VP1]

Hey all,
On my 1980 1100E, I notice that if I take a sweeper at upwards of 80MPH I'll start to get a little head shake. It never progresses into anything serious, but I can definitely feel a little uncomfortable wobble starting.

Bike has about 43,000 miles and is in decent condition. Shocks could probably use renewing but I've certainly rode on far worse.

So what do you think? Just part of riding an old bike with a flexy frame or could this be cured?

Thanks, Todd

 

[omaharj]

Hey all,
On my 1980 1100E, I notice that if I take a sweeper at upwards of 80MPH I'll start to get a little head shake. It never progresses into anything serious, but I can definitely feel a little uncomfortable wobble starting.

Bike has about 43,000 miles and is in decent condition. Shocks could probably use renewing but I've certainly rode on far worse.

So what do you think? Just part of riding an old bike with a flexy frame or could this be cured?

Thanks, Todd

It's absolutely NOT part of riding an older bike. I don't think you should be taking sweepers at 80 until you get it figured out. The original front shocks were a bit light,many members have gone to progressive. That would be my first thing.
More knowledgeable people will be responding shortly.:dancing: RJ
BTW Welcome to the GSR (I noticed I said front shocks instead of forks,what a well-mannered group to not point that out...comes from good breeding.hehe)

 

[bwringer]

Swingarm and steering stem bearings will also cause this, as well as tires, wheel bearings

If the shocks are original junk, they will also cause wallowing and weaving in sweepers. Same with the forks -- if they are not wearing upgraded springs and fresh oil, or if you're relying on air pressure instead of installing correct springs, you can have all sorts of oddities.

A GS can and should be stable in far more intense cornering than what you describe -- instability is NOT inherent as it was with other bikes of the era. Something is wrong.

 

[don_gibb6512]

Ditto on the previous statements. BWRinger hit the nail on the head.

"Swingarm and steering stem bearings will also cause this, as well as tires, wheel bearings" and rear shocks.

Make sure your chain is in good shape and aligned correctly too and THEN take the 80mph sweeper again and see how it feels.

And a fork brace will help also.

Good luck. and BTW, I take 80mph sweepers all the time on my '80. When you've got it tight, they're FUN !!

 

[Spyderman]

Hey all,
On my 1980 1100E, I notice that if I take a sweeper at upwards of 80MPH I'll start to get a little head shake. It never progresses into anything serious, but I can definitely feel a little uncomfortable wobble starting.

Bike has about 43,000 miles and is in decent condition. Shocks could probably use renewing but I've certainly rode on far worse.

So what do you think? Just part of riding an old bike with a flexy frame or could this be cured?

Thanks, Todd

well my first thought is that your front tire is worn and cupped the usual cause is either over inflation or under inflation this will cause a head shake

it also could be caused by a rear tire that is squared off and you could be trying to ride on that squared edge in the sweeper and it will cause the bike to shake its head

it could also be your steering head bearings to tight or too loose

or it might be your suspension weak fork springs also weak or sticking rear shocks can do it as well

i would start by closely inspecting your tires front and rear if they look suspect then replace them
if the problem still persists then
next i would check the steering head bearings to be sure that you have easy smooth movement with no play in them if it notches or you find play them tighten or replace them and check the swingarm for play in the bearings
if the problem still persists then
then i would move on to checking your front and rear suspension for ride height stiffness and that the shocks are not sticking or too soft

i hope that this give you a direction to go in
and that you get this problem solved

 

[Spyderman]

Good luck. and BTW, I take 80mph sweepers all the time on my '80. When you've got it tight, they're FUN !!

if you find good sweepers then 80 can be slow going through them
and your right when you get it right and the bike is stable then doing those sweepers at 100+ is just way too much fun

and good call on the chain alignment
poorly aligned wheels can also be a cause

 

[VP1]

Thanks guys.

Little more info-

Brand new Shinko Tourmaster tires.
Brand new chain and sprockets.

I checked the rear swing arm for bearing play while changing the sprockets and couldn't detect any. Doesn't mean there isn't any, but I couldn't feel it.

The steering head bearings feel ok but I'll double check them.

I'm kind of thinking shocks. Some progressive springs will probably be going in pretty soon.

I'll just keep replacing things till it goes away

In the mean time I'll keep it a little slower out in the hills

And I've been meaning to ask, any tire pressure recommendations for my bike? Like I said, it has new Shinko Tourmasters. I have fun with the cc's and typically ride in a "sporty" manner if that makes a difference.

Thanks!

 

[Spyderman]

Thanks guys.

Little more info-

Brand new Shinko Tourmaster tires.
Brand new chain and sprockets.

I checked the rear swing arm for bearing play while changing the sprockets and couldn't detect any. Doesn't mean there isn't any, but I couldn't feel it.

The steering head bearings feel ok but I'll double check them.

I'm kind of thinking shocks. Some progressive springs will probably be going in pretty soon.

I'll just keep replacing things till it goes away

In the mean time I'll keep it a little slower out in the hills

And I've been meaning to ask, any tire pressure recommendations for my bike? Like I said, it has new Shinko Tourmasters. I have fun with the cc's and typically ride in a "sporty" manner if that makes a difference.

Thanks!

well now with this new info i would then lean towards your suspension
think about progressive springs in the front with 15 weight fork oil and new shocks on the back
as for tire pressures i have metzeler tires and i run 32 PSI in the front and 36 PSI in the rear this works well for me on a nice spirited ride in the mountains

when you check te steering head bearings do it
with the wheel off the ground check for nice smooth side to side motion no notching
grab the bottom of the forks and check for any movement back and forth and then side to side

 

[VP1]

Thanks for the great advice.

I'll post results as they come.

 

[TheCafeKid]

Not trying to be an ass or anything? But assuming any one of those things is ok is not the way to go. They all should be checked at least and if there is any question on thier life I'd simply replace them. Head or stem bearings as some refer to them, can be checked by getting the bike off the front wheel and moving the forks back and forth slowly. If you feel any sort of notching or ratcheting the bearing races are toast. They develop little detents in them over time and then will cause head shake as they rock in and out of those detents. Most noticeable at higherspeeds, and god help you if that front wheel starts freaking outat speed. That's a good way to start a tank slapper too and if you've never experienced one, using instincts and fighting the bars to stop it wi get you hurt. IMO a tankslapper is probably the scariest happening to be involved in because to stop it you simply have to let go of the bars when every part of your being is telling you not to. Lol. Anyway, wheels bearing are somethig else I would check and yes, fork springs and replace the fork oil too. That should be done every season or two if you really put miles on your bike. Also if you haven't replaced the oil already, I would suggest it simply because an imbalance of Less than a milliliter, according to the shop manual, will also cause fork stress issues. Also, if you're planning on cooking it in sweepers often, I'd invest in better tires. I know you said you just bought those, but really good tires are seriously confidence inspiring. It can be a night and day difference.
In short, your GS, properly shod and sprung, will handle better than your "pucker factor" will likely allow it. High speed wobbles are NOT a GS trait, but updating the springs shocks tires and bearings are pretty much a requirement if the bike is new to you or the mantainence history is questionable. Get her sorted be safe and enjoy

 

[VP1]

Great advice and I will certainly follow all of it.

Thanks much!

 

[woodman]

I have an 80 GS1100 with the same problem. This is info I got at Bonneville from the guy who ran the first GS1100 4 valve that was shipped to Canada, none were in the US yet. The first pass he made at Bonneville the bike scared the crap out of him from a speed wobble. They then put the bike in a chassis jig and found the steering heads welded on off center, the front & rear wheels didnt track the same. After fixing that the front & rear wheels were trued on a lathe,also not correct. The bike was also very sensitive to tires. With all that done he set a number of records with it. His name is Jack Dolan and he has and still does hold a number of records at Bonneville both on bikes and in cars & worked for US Suzuki at the time. What Im telling you is what he told me, I dont claim to be an expert. Hope this helps your problem. He also stated that they put new Kawasaki Z1s & KZ 1000s on the jig and found the same problems when he worked for US Kawasaki in the early 70s. Dont shoot the messenger !

 

[Guest]

That's a good way to start a tank slapper too and if you've never experienced one, using instincts and fighting the bars to stop it wi get you hurt. IMO a tankslapper is probably the scariest happening to be involved in because to stop it you simply have to let go of the bars when every part of your being is telling you not to.

Is this a good method to control a tank slapper situation? Haven't experienced one myself, but a friend with a highly modded GS1100 did, probably because the geometry was altered considerably from stock. For most riders, they seem to begin when the the throttle is abruptly chopped after accelerating to high speeds (over 140 mph, in his case), and he was able to regain control by getting back on the gas, unloading the front wheel. Haven't heard about letting go of the bars, but yes, that would not come naturally at those speeds.
Tony.

 

[Turtleface]

Is this a good method to control a tank slapper situation? Haven't experienced one myself, but a friend with a highly modded GS1100 did, probably because the geometry was altered considerably from stock. For most riders, they seem to begin when the the throttle is abruptly chopped after accelerating to high speeds (over 140 mph, in his case), and he was able to regain control by getting back on the gas, unloading the front wheel. Haven't heard about letting go of the bars, but yes, that would not come naturally at those speeds.
Tony.

I'd be willing to bet that while concentrating on throttle control, your friend subconsciously relaxed his arms, allowing the bike's caster to settle out the front end. You don't necessarily have to take your hands of the controls, but you do have to relax enough to let physics work. A neat habit I've tried to develop is to tighten my thighs whenever I get into any sort of tense situation. I stick on the bike real good, and I get to get my nerves out through my leg muscles, leaving my hands and feet relaxed so they can do their things.

 

[Roostabunny]

I've got four broken ribs as a reminder of why I should NOT have put up with a little shake. One of these days it'll happen at the wrong time.

I've got a recent crash messing with my objectivity, but in my mind it's shifted from the "nice upgrade" list to the "safety issue" list, and I'll be making my long overdue suspension upgrades before I ride mine again.

In short, these bikes are renowned for stability - listen to the advice from these other guys.

 

[twr1776]

Todd, I agree with the opinions to check EVERYTHING mentioned. The two things I would not bother checking is the fork springs and shocks. If they are OEM you should just junk them for new ones. Yes it is not cheap but for about $ 300 you can get a good set of replacements fronk and back. Do you have any kind of shield on it? An improperly angled or lined up shield can also cause head shake. I found this out the hard way but fortunately was able to keep the bike under control and after lining it up correctly and changing the angle, problem solved.

 

[bonanzadave]

Last time I mentioned tank slapper here I got crucified . When my bike was new I could roll the throttle for five miles and it was as solid as a rock. After about 20K miles it would get loose at triple digits. I did everything mentioned (except tires) and it got much better. Tires are next. I lived with it for a few years and managed the control by gradually decelerating and pulling down on the bars. I think this may have been a factor of the loose steering bearings. Not a good feeling. Now its got All Balls, Progressive and swing arm bearings. After the tires my next fix will be keeping it below 100mph .

 

[TheCafeKid]

Is this a good method to control a tank slapper situation? Haven't experienced one myself, but a friend with a highly modded GS1100 did, probably because the geometry was altered considerably from stock. For most riders, they seem to begin when the the throttle is abruptly chopped after accelerating to high speeds (over 140 mph, in his case), and he was able to regain control by getting back on the gas, unloading the front wheel. Haven't heard about letting go of the bars, but yes, that would not come naturally at those speeds.
Tony.

Well, Its worked for me I rode dirt for years and years, and most of the tank slappers I have experienced werent at tripple digit speeds to say the least. The way I have always understood the dreaded tankslapper is this: the more you fight the bars to get them under control, the worse the bike fights you back. Most of the 'slappers ive experienced started one of two ways; The front wheel, once airbourne, came down out of line with the rear wheel, and the bike, under power, wants to straighten itself out simply because of the physics of a motorcycle. So, the bars jerk one direction or the other. The problem begins when the throttle either gets slapped shut, or wacked open. This doesnt seem like a big deal just reading it, but it generally happens so fast, your first instinct is to jerk the bars back, thus doing the opposite to the throttle that the bike did to you. This starts a chain reaction, an almost hobby horse effect, the CG keeps shifting from front to back as the throttle comes on and off, the bike keeps trying to right itself, and you, in essence, are fighting it. Because the bike, naturally while in motion, wants to go straight, and upright, I was always taught to just let go, just for a second. The bike will right itself. Now, this may not be the true definition of a "tankslapper" but the action pretty much resembles exactly what happens in a high speed tank slapper.

The scariest time it ever happened to me was a couple years ago in Elkins, WV. I was out there with Steve and the Goldwing group, and we were leaving the hotel that morning to start the days ride. The group leaders had blocked traffic coming from the left, so our group could pull out of the motel parking lot. But no one had stopped it coming from the right. Some jerk in an SUV decided he didnt possibly have the time to wait for our 10 or so bikes to pull out, so he tried to cut into the line of bikes right as I was rolling thru the median. He was gonna mow me down more or less. So i goosed the throttle to get the hell out of his way. Well at the time I didnt know what had really happened, but as soon as I goosed it, the front wheel came up just a bit (i was cresting a hill) and when it came back down the bars went buck crazy.. they slammed hard left, then back to the right, and back and forth. After probably the third time it jerked my arms, i just let go. It wasnt really a concious descision, just wrote memorization I suppose. But I let go. Just for a second. And the bars jerked back to the left hard, and then came back to center and I was going straight again. I gave her some throttle and booked it out of his way. At first, I was ticked at myself, cause I thought it was my fault for jumping on the throttle first thing in the morning on cold cold tires. But i found out at our first stop that the person behind me saw everything. She asked how I managed not to go down. I said that I really didnt know, I thought that I was going to to be honest. I had apparently ran through a patch of asphault coloured sand more or less, and when I goosed it, the rear tire gripped hard at first, and once it got into the sand it busted loose and she said the bike looked like i was on a bucking bronco. the front end was going one way, and the rear end the other. That was pretty damn butt puckering I can say that... But, I didnt go down, and I figure if I had hung on, and fought the bars, I probably would have.

Sorry for the long 'jack

 

[teddux]

...replace the fork oil too. That should be done every season or two if you really put miles on your bike. Also if you haven't replaced the oil already, I would suggest it simply because an imbalance of Less than a milliliter, according to the shop manual, will also cause

On my Nighthawk, a simple "imbalance" of air pressure IN FORKS would cause this.

 

[TheCafeKid]

On my Nighthawk, a simple "imbalance" of air pressure IN FORKS would cause this.

Yeah, Im not sure how much i believe this.. But, if they saw fit to print it, It probably should be taken into consideration. The manual states that improper oil or air levels in the forks, or uneven levels, will cause stress on the axle, stress on the fork walls, yadda yadda yadda. I measured carefully, but Im sure its not EXACTLY even. Ive never had a problem, but I do try VERY hard to follow their suggestions..