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101Back to top Go down   K100RS Steering wobble: All potentials - Page 3 Empty Re: K100RS Steering wobble: All potentials on Wed Mar 27, 2013 5:55 pm

Tenox


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Yep, had 1999 TRX 06 - 09 and liked it a lot. One of the best bikes I have had. Picture of my ex TRX can be found here: https://www.dropbox.com/sh/amqoywn9u69t1op/HUDvE8Hx3F among other ex bikes. I have been riding first 90-91 with 125cc and then 2002 (FZS600) and after a little break from 2006 to today and planning to continue as long as I can. So this is only 9th season with bigger bikes and K is my 11th bike.  Laughing  Been searching for the right one?



Last edited by Tenox on Tue May 13, 2014 5:44 pm; edited 2 times in total

    

102Back to top Go down   K100RS Steering wobble: All potentials - Page 3 Empty Re: K100RS Steering wobble: All potentials on Wed Mar 27, 2013 6:10 pm

dmanley

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@Tenox wrote:Yep, had 1999 TRX 06 - 09 and liked it a lot. One of the best bikes I have had. Picture of my ex TRX can be found here: http://kotisivu.dnainternet.net/ajk73/download.html among other ex bikes. I have been riding first 90-91 with 125cc and then 2002 (FZS600) and after a little break from 2006 to today and planning to continue as long as I can. So this is only 9th season with bigger bikes and K is my 11th bike. Laughing Been searching for the right one?

The cafe looks great. Nice work!


__________________________________________________
Daryl

1985 K100RT
    

103Back to top Go down   K100RS Steering wobble: All potentials - Page 3 Empty Re: K100RS Steering wobble: All potentials on Wed Mar 27, 2013 6:56 pm

ShedBob

ShedBob
active member
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Just thought I'd say a quick thanks to you guys.
Prepping my K100RT for the MOT yesterday & was mortified by how stiff the steering was with a pronounced preference for the straight ahead position. Was all set to buy new head bearings when I read some threads & decided to try a quick squirt with some WD40 instead. Instant resolution of stiffness & free turning lock to lock.
So now I know my bearings are ok & just need regreasing.
You just saved me £20 in bearings.
Thanks chaps !

    

104Back to top Go down   K100RS Steering wobble: All potentials - Page 3 Empty I have on Wed Mar 27, 2013 7:34 pm

ibjman

ibjman
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I have a 1970 Moto-Guzzi that's been SO stiff for years, that you can barely get it around a left hand turn without falling off!.....LOL
I've been avoiding taking it apart since I only drive it once a year to & from the Arizona Emissions inspection Station, in favor of more pressing projects.
Maybe I'll try some WD as a temporary help till I get around to fixing it. Thanks for the tip!!!
I guess I'll need to get the front drum brake operational some day soon also....LOL
Between the steering and the brakes and a throttle that's so stiff it hurts your arm......It's a real Hoot to drive.

    

105Back to top Go down   K100RS Steering wobble: All potentials - Page 3 Empty Re: K100RS Steering wobble: All potentials on Thu Mar 28, 2013 12:54 am

Themason

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[quote="ShedBob"]Just thought I'd say a quick thanks to you guys.
Prepping my K100RT for the MOT yesterday & was mortified by how stiff the steering was with a pronounced preference for the straight ahead position. Was all set to buy new head bearings when I read some threads & decided to try a quick squirt with some WD40 instead. Instant resolution of stiffness & free turning lock to lock.
So now I know my bearings are ok & just need regreasing.
You just saved me £20 in bearings.
Thanks chaps ![/quote]




You aren't the one who siliconed the clutch spring in are you, lol? :suspect:



Last edited by Themason on Thu Mar 28, 2013 3:00 pm; edited 1 time in total


__________________________________________________
I live in a parallel universe but have a vacation home in reality :arrow:

1984 K-100RS Alaska Blue w/Parelever and 16V wheels.

1984 K-100RS Metallic Madison stock

1986 R-80G/S w/1000 cc engine

2007 Harley Davidson Street Rod Mirage Orange w/XR1200 wheels, Race Tech, True Track, Works Performance shocks

2007 Harley Davidson Street Rod Vivid Black stock

1993-ish K-100/1100RT/LT hemaphrodite frankenbike thingy to be painted satin black from a rattle can eventually
    

106Back to top Go down   K100RS Steering wobble: All potentials - Page 3 Empty Re: K100RS Steering wobble: All potentials on Thu Mar 28, 2013 4:36 am

dalderton

dalderton
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From a person who made a living for 15 years straightening frames. 1 Never experienced an original frame running the wheels out of line. 2 Could not possibly contribute to stability. 3 It would be physically impossible for a standard road frame to "run out of trail when the forks are fully compressed" The trail would reduce slightly but not to the point of being dangerous. In all my time working on frames no one has ever mentioned or blamed that for anything. Steering head races are the most likely cause of wobbles ,swing arm pivots because of wear or bad design can also do it.Bad damping or spring rates on forks or back shock can also be culprits. Steering geometry on some bikes can contribute to it plus a combination of all or some of the above. Incidentally I reckon the rubber and silicone grease damper in my K75 is the greatest thing since sliced bread.
Regards Dennis.


__________________________________________________
1985 K75c Stock other than Realm Engineering Rear Shock.
    

107Back to top Go down   K100RS Steering wobble: All potentials - Page 3 Empty Re: K100RS Steering wobble: All potentials on Thu Mar 28, 2013 3:10 pm

Themason

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[quote="dalderton"]From a person who made a living for 15 years straightening frames. 1 Never experienced an original frame running the wheels out of line. 2 Could not possibly contribute to stability. 3 It would be physically impossible for a standard road frame to "run out of trail when the forks are fully compressed" The trail would reduce slightly but not to the point of being dangerous. In all my time working on frames no one has ever mentioned or blamed that for anything. Steering head races are the most likely cause of wobbles ,swing arm pivots because of wear or bad design can also do it.Bad damping or spring rates on forks or back shock can also be culprits. Steering geometry on some bikes can contribute to it plus a combination of all or some of the above. Incidentally I reckon the rubber and silicone grease damper in my K75 is the greatest thing since sliced bread.
Regards Dennis.[/quote]

If the fork is compressed enough in a corner due to weight and cornering loads, the bike certainly can become unstable. It isn't just K bikes that have this problem. Some early V-Rod models and all the airhead twins except the R100R suffer the same thing. The cure is to reduce the offest in the triple clamp to increase trail. If you compare triple clamps between a 1970s to late 1980's flat twin to those on the R100R, you will see this is exactly what BMW did. The offset of the R100R triple clamp is about 15 mm less than you would find on a late 1980's flat twin. A friend makes a set of triple clamps for early Rs with a similar reduction in offset and that cures the weaves and wobbles those old twins have. I think you will find the triple clamps of 16V Ks have less offset than those of original K100s or those of the K75. Likewise HD added trail to later V-Rod models to cure their high speed instability. Adrenaline Moto sells Harris billet triple clamps with reduced offset for Harley XR1200s for the same reason. It is especially necessary if you run long shocks. You do not need a steering damper for road racing these things if you can get a bit more trail on them. The part is not legal for AMA racing but is common fair on XRs raced in the several European series that feature those bikes.

On the Blue Bovine in my avatar, I am running R100GS triple clamps. They have about 15 mm less offset than the originals, but the machining required to make them fit a K, and to mount instruments and the dash pad is not for the feint of heart. It ends up costing as much to do as buying a premium fully adjustble remote reservoir shock and don't try it unless you know someone who has done this a few times.

More trail is what cures the weaves and wobbles on these bikes. I know because I have done it, and because I have a stock K for comparison.


__________________________________________________
I live in a parallel universe but have a vacation home in reality :arrow:

1984 K-100RS Alaska Blue w/Parelever and 16V wheels.

1984 K-100RS Metallic Madison stock

1986 R-80G/S w/1000 cc engine

2007 Harley Davidson Street Rod Mirage Orange w/XR1200 wheels, Race Tech, True Track, Works Performance shocks

2007 Harley Davidson Street Rod Vivid Black stock

1993-ish K-100/1100RT/LT hemaphrodite frankenbike thingy to be painted satin black from a rattle can eventually
    

108Back to top Go down   K100RS Steering wobble: All potentials - Page 3 Empty Re: K100RS Steering wobble: All potentials on Fri Mar 29, 2013 12:08 am

RicK G

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@dalderton wrote:From a person who made a living for 15 years straightening frames. 1 Never experienced an original frame running the wheels out of line. 2 Could not possibly contribute to stability. 3 It would be physically impossible for a standard road frame to "run out of trail when the forks are fully compressed" The trail would reduce slightly but not to the point of being dangerous. In all my time working on frames no one has ever mentioned or blamed that for anything. Steering head races are the most likely cause of wobbles ,swing arm pivots because of wear or bad design can also do it.Bad damping or spring rates on forks or back shock can also be culprits. Steering geometry on some bikes can contribute to it plus a combination of all or some of the above. Incidentally I reckon the rubber and silicone grease damper in my K75 is the greatest thing since sliced bread.
Regards Dennis.

Thats fairly right Dennis I just did some calculations on my CAD program and the standard trail is 105mm and reduces down to 87mm under brakes with full compression of 185mm and even with the tyre flattened out to 30% of its normal height it is reduced to only 82mm. To get the trail to reduce to zero you would need to have the rear wheel over 500mm of the ground.
No wonder doing a stoppie is a bit unnerving.


__________________________________________________
"Man sacrifices his health in order to make money.
Then he sacrifices money to recuperate his health.
And then he is so anxious about the future that he does not enjoy the present; the result being that he does not live in the present or the future; he lives as if he is never going to die, and then dies having never really lived."   Dalai Lama


Bikes 1993 K1100 LT, 1998 K1100 LT, 1993 K75 RT, 1996 K75RT, 1986 K75 GS, 1979 Z1300 Kawasaki X 2 for now
    

109Back to top Go down   K100RS Steering wobble: All potentials - Page 3 Empty Re: K100RS Steering wobble: All potentials on Fri Mar 29, 2013 12:29 am

Themason

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The motorcycles trail does not have to degrade down to zero to develop a serious weave. Much less than 90 mm of trail is asking for trouble. There has to be enough trail to overcome the forces trying to destabilize the bike. That means positive trail. At zero trail the handlebars would whip out of your hands. Ever had a shopping cart with a wheel that kept wobbling side to side? That is from lack of trail. In cars it is called caster. In bikes a front wheel behaving like that would not be ridable.
Your CAD measurements also neglect to consider the effects of lean angle, steering angle and fork compression during cornering on trail. All three of these act to reduce trail, in the case of stock K100s to a point where trail is insufficient to overcome the other forces trying to destabilize the bike.


__________________________________________________
I live in a parallel universe but have a vacation home in reality :arrow:

1984 K-100RS Alaska Blue w/Parelever and 16V wheels.

1984 K-100RS Metallic Madison stock

1986 R-80G/S w/1000 cc engine

2007 Harley Davidson Street Rod Mirage Orange w/XR1200 wheels, Race Tech, True Track, Works Performance shocks

2007 Harley Davidson Street Rod Vivid Black stock

1993-ish K-100/1100RT/LT hemaphrodite frankenbike thingy to be painted satin black from a rattle can eventually
    

110Back to top Go down   K100RS Steering wobble: All potentials - Page 3 Empty Re: K100RS Steering wobble: All potentials on Fri Mar 29, 2013 12:42 am

RicK G

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@Themason wrote:
Find a diagram of the front end geometry of a motorcycle and see how trail is drawn. As the fork is compressed and/or rear suspension raised on the shock, you reduce trail. As squishy as the stock suspensions are, you can get them to pitch nose down sufficiently to eat up all the trail and get into a very scary weave if you are going fast. Harder springs limit the amount of pitching and bouncing from these bikes, so you don't get into that nose down conditon as easily as you do with the stock springs, but don't ever get too comfortable with that idea. If you enter a turn fast enough with enough weight on the bike, even with "premium" suspension components you can still compress the front suspension enough to run out of trail and enter what I call the "death weave". You will never forget it if you ever experience one. Both ends cycle through their full travel while the bars weave nearly full lock. So much for hard springs and remote reservoir shock.

QED


__________________________________________________
"Man sacrifices his health in order to make money.
Then he sacrifices money to recuperate his health.
And then he is so anxious about the future that he does not enjoy the present; the result being that he does not live in the present or the future; he lives as if he is never going to die, and then dies having never really lived."   Dalai Lama


Bikes 1993 K1100 LT, 1998 K1100 LT, 1993 K75 RT, 1996 K75RT, 1986 K75 GS, 1979 Z1300 Kawasaki X 2 for now
    

111Back to top Go down   K100RS Steering wobble: All potentials - Page 3 Empty Sorry on Fri Mar 29, 2013 12:52 am

ibjman

ibjman
Life time member
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Sorry, I don't get the point of all this controversy about "trail".
I will assume for a moment that the point is made
Simply said (if I have it correct?).......a reduction in front geometry "trail" leads to oscillations (or what most of us call wobble, shimmy, tank slapper or whatever), as well as a host of other possible causes (tire wear, inflation pressure, loose or bent parts, unconscious operator, etc.....
The point (IMO) has been readily made that it is possible (probable) to encounter this condition.
I believe the object of the thread was "what to do about it"?
in the absence of some catastrophic wear, bent stuff or unusual condition (un-likely)....
Can some of us generally agree that creating some "drag" or dampening in the steering head will keep it from occurring?
I think that point is well made.....we should close this thread & move on.
Your thoughts?

    

112Back to top Go down   K100RS Steering wobble: All potentials - Page 3 Empty Re: K100RS Steering wobble: All potentials on Sun Mar 31, 2013 6:30 am

Be made

Be made
Life time member
Life time member
I disagree. Keep the thread open. Something may come to light at some point in the future that may benefit someone, you never know, but for now . . here's a little dated info that can be put to use

immediately
Just ride sensibly and you'll be fine . . happy trails pardner . . . K100RS Steering wobble: All potentials - Page 3 22936

    

113Back to top Go down   K100RS Steering wobble: All potentials - Page 3 Empty Re: K100RS Steering wobble: All potentials on Sun Mar 31, 2013 6:40 am

Be made

Be made
Life time member
Life time member
@ShedBob wrote:Just thought I'd say a quick thanks to you guys.
Prepping my K100RT for the MOT yesterday & was mortified by how stiff the steering was with a pronounced preference for the straight ahead position. Was all set to buy new head bearings when I read some threads & decided to try a quick squirt with some WD40 instead. Instant resolution of stiffness & free turning lock to lock.
So now I know my bearings are ok & just need regreasing.
You just saved me £20 in bearings.
Thanks chaps !

Haynes, again:

K100RS Steering wobble: All potentials - Page 3 Steeee

For those who wish to repair, for another 100,000 ks. This I know because my machine @ 110,000 has stuffed steering head bearings. Sorry mate but WD40 just doesn't quite cut it for me . . . I think the indexing is due a little more to wear and tear than anything else. Replacement really is the best option . . for life, but thanks for your results report anyway shedbob

    

114Back to top Go down   K100RS Steering wobble: All potentials - Page 3 Empty Re: K100RS Steering wobble: All potentials on Sun Mar 31, 2013 7:25 am

RicK G

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I will just drop a word in here for the unwary.
I bought a set of head bearings on fleabay and was assured by the seller that they were "the best bearings that money could buy" I was a biy wary but thought I would give it a go. The seller is Pyramid parts from NZ and he sells fork seals, swing arm bearings and a few other bits for our Ks. Now its your choice but don't throw your money away I got 11000klm from the set of head bearings so to say garbage is an understatement.
I approached him and said that I wanted my dollars back and he did the old trick "that was not me I bought the business so its a different company go wistle for your money.
The down side of the internet shopping mall.


__________________________________________________
"Man sacrifices his health in order to make money.
Then he sacrifices money to recuperate his health.
And then he is so anxious about the future that he does not enjoy the present; the result being that he does not live in the present or the future; he lives as if he is never going to die, and then dies having never really lived."   Dalai Lama


Bikes 1993 K1100 LT, 1998 K1100 LT, 1993 K75 RT, 1996 K75RT, 1986 K75 GS, 1979 Z1300 Kawasaki X 2 for now
    

115Back to top Go down   K100RS Steering wobble: All potentials - Page 3 Empty Re: K100RS Steering wobble: All potentials on Sun Mar 31, 2013 9:08 am

Crazy Frog

Crazy Frog
admin
admin
[quote="bemade"]
@ShedBob wrote:Just thought I'd say a quick thanks to you guys.
Prepping my K100RT for the MOT yesterday & was mortified by how stiff the steering was with a pronounced preference for the straight ahead position. Was all set to buy new head bearings when I read some threads & decided to try a quick squirt with some WD40 instead. Instant resolution of stiffness & free turning lock to lock.
So now I know my bearings are ok & just need regreasing.
You just saved me £20 in bearings.
Thanks chaps !

This is the solution that I used when testing my K100 before deciding to go for a complete rebuilt. It was only temporary but helped me to keep the bike on the road for an extra month.
The original problem was not really the bearing itself, but the grease had dried and turned into a very sticky varnish.

During the rebuilt, the bearings were replaced.

CF


__________________________________________________
K100RS Steering wobble: All potentials - Page 3 Frog15K100RS Steering wobble: All potentials - Page 3 Logo2101986 k75, 1985 K100rt, 1985 K100rt/EML GT2 sidecar, 1999 K1200lt/Hannigan Astro Sport sidecar.
    

116Back to top Go down   K100RS Steering wobble: All potentials - Page 3 Empty Re: K100RS Steering wobble: All potentials on Sun Mar 31, 2013 2:59 pm

Tenox

Tenox
Life time member
Life time member
Just wanted to say that mine is stable at atleast speeds up to 160km/h. In Finland top speed on highway is 120km/h so I should be fine on normal day to day driving. Still wondering about those bearings though.. Might have to tighten them a bit stil before the airfield run.

Edit: Stable even without hands on bars, so I guess it is OK.



Last edited by Tenox on Thu Apr 04, 2013 10:20 am; edited 1 time in total


__________________________________________________
BMW K100RT Scrambler (86)
    

117Back to top Go down   K100RS Steering wobble: All potentials - Page 3 Empty Re: K100RS Steering wobble: All potentials on Sun Mar 31, 2013 5:16 pm

K-BIKE

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Good stuff,
Thanks for the tip Rick G I could easily have fallen for that one being in country and all, bad luck for you though mate to have to re-do the job in no time at all.
Regards,
K-BIKE

    

118Back to top Go down   K100RS Steering wobble: All potentials - Page 3 Empty Re: K100RS Steering wobble: All potentials on Sun Mar 31, 2013 9:28 pm

dalderton

dalderton
active member
active member
@Rick G wrote:I will just drop a word in here for the unwary.
I bought a set of head bearings on fleabay and was assured by the seller that they were "the best bearings that money could buy" I was a biy wary but thought I would give it a go. The seller is Pyramid parts from NZ and he sells fork seals, swing arm bearings and a few other bits for our Ks. Now its your choice but don't throw your money away I got 11000klm from the set of head bearings so to say garbage is an understatement.
I approached him and said that I wanted my dollars back and he did the old trick "that was not me I bought the business so its a different company go wistle for your money.
The down side of the internet shopping mall.


I had the same result with a set of fork seals for CX500. Very short life span.I got a set of genuine and problem solved


__________________________________________________
1985 K75c Stock other than Realm Engineering Rear Shock.
    

119Back to top Go down   K100RS Steering wobble: All potentials - Page 3 Empty Re: K100RS Steering wobble: All potentials on Mon Apr 01, 2013 5:06 am

Albyalbatross1

Albyalbatross1
Life time member
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I have noticed after changing tyres today..the wobble is gone. Same thing with last set of tyres.. New steering bearings first job on list when bought the old girl. i am leaning towards tyre wear and fork alignment.

    

120Back to top Go down   K100RS Steering wobble: All potentials - Page 3 Empty Re: K100RS Steering wobble: All potentials on Mon Apr 01, 2013 5:17 am

charlie99

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good result alby ....what did you put on ...?

i have a feeling that minor disc and rim variations cause wear in constant places on the tyre .. not noticeable for most of its life ...but ...time and braking goes on huh ?

happy riding mate ...!


__________________________________________________
cheezy grin whilst riding, kinda bloke ....oh the joy !!!! ...... ( brick aviator )

'86 K100 RT..#0090401 ..."Gerty" ( Gertrude Von Clickandshift ) --------O%OK100RS Steering wobble: All potentials - Page 3 Au-log10

'86 k100 rs.. #######..  "Fred " (f(rame) red ) ( Fredrick leichtundschnell ) - -
bits and pieces from many kind friends across the k100 world ...with many thanks ..
    

121Back to top Go down   K100RS Steering wobble: All potentials - Page 3 Empty Re: K100RS Steering wobble: All potentials on Tue Apr 02, 2013 6:16 am

88

88
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Having been the one who revived this thread I can say I have read all the contributions including the less relevant ones and having checked the bike over, all bearings etc, I am of the opinion that uneven tyre wear due to the cambers on the back roads much of my riding is done on and a faulty or under reading forecourt guage on the last outing.

88


__________________________________________________
K100RS Steering wobble: All potentials - Page 3 Ir-log11 88....May contain nuts!K100RS Steering wobble: All potentials - Page 3 Ir-log11

"The world is a book and those who do not travel read only one page." - St. Augustine from 1600 years ago & still true!

Bike: K100LT 1988. 0172363. AKA the Bullion Brick! Mods: k1100 screen and stands.
K1: 1990. 6374189. Custom Stealth Black paint.
    

122Back to top Go down   K100RS Steering wobble: All potentials - Page 3 Empty Re: K100RS Steering wobble: All potentials on Tue Apr 02, 2013 7:17 pm

Toto_jp

avatar
Platinum member
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If or when I finally get in the seat of my K I can see a lot of head stem shaking
coming from the front end it won't be the bike it ill be the pilot (me )
shaking with excitement Smile

cheers Tony


__________________________________________________
K100 RS 1986
    

123Back to top Go down   K100RS Steering wobble: All potentials - Page 3 Empty Re: K100RS Steering wobble: All potentials on Wed Apr 03, 2013 6:43 am

charlie99

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lol!


__________________________________________________
cheezy grin whilst riding, kinda bloke ....oh the joy !!!! ...... ( brick aviator )

'86 K100 RT..#0090401 ..."Gerty" ( Gertrude Von Clickandshift ) --------O%OK100RS Steering wobble: All potentials - Page 3 Au-log10

'86 k100 rs.. #######..  "Fred " (f(rame) red ) ( Fredrick leichtundschnell ) - -
bits and pieces from many kind friends across the k100 world ...with many thanks ..
    

124Back to top Go down   K100RS Steering wobble: All potentials - Page 3 Empty Re: K100RS Steering wobble: All potentials on Fri Apr 05, 2013 7:38 pm

Albyalbatross1

Albyalbatross1
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@charlie99 wrote:good result alby ....what did you put on ...?

I put good old batlax on. I wacked the old tyres from my RS on theother K and I have just gone for 50 k run and and the bike I had no wobble on now has wobble from 60- 80 kph. Tyre pressures the same on each bike..39psi front and 42 rear.

I think I will now follow the suggestion of charlie and have the balance done again the rims with worn down tyres and just see what happens. I will post teh results.

    

125Back to top Go down   K100RS Steering wobble: All potentials - Page 3 Empty Re: K100RS Steering wobble: All potentials on Tue Apr 09, 2013 1:15 pm

ShedBob

ShedBob
active member
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[quote="Crazy Frog"]
bemade wrote:
@ShedBob wrote:Just thought I'd say a quick thanks to you guys.
Prepping my K100RT for the MOT yesterday & was mortified by how stiff the steering was with a pronounced preference for the straight ahead position. Was all set to buy new head bearings when I read some threads & decided to try a quick squirt with some WD40 instead. Instant resolution of stiffness & free turning lock to lock.
So now I know my bearings are ok & just need regreasing.
You just saved me £20 in bearings.
Thanks chaps !

This is the solution that I used when testing my K100 before deciding to go for a complete rebuilt. It was only temporary but helped me to keep the bike on the road for an extra month.
The original problem was not really the bearing itself, but the grease had dried and turned into a very sticky varnish.

During the rebuilt, the bearings were replaced.

CF

Just in case you were all worrying that I thought I'd fixed my notchy steering with some WD40. I did actually follow up by stripping the steering head & forks out to check the bearings. Bearings & tracks were fine so I cleaned off all the original 1984 grease, repacked & replaced. Bit of adjusting of the preload & all is well.
MOT gained, steering improved, what's not to like ?

    

126Back to top Go down   K100RS Steering wobble: All potentials - Page 3 Empty Re: K100RS Steering wobble: All potentials on Mon May 12, 2014 9:28 pm

Be made

Be made
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. . . .so I cleaned off all the original 1984 grease, repacked & replaced. Bit of adjusting of the preload & all is well.
MOT gained, steering improved, what's not to like ?
Nice. great result man. well done and saved ya a lot of dollars Smile

    

127Back to top Go down   K100RS Steering wobble: All potentials - Page 3 Empty Re: K100RS Steering wobble: All potentials on Tue May 27, 2014 9:28 am

Snod Blatter

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This is suddenly a very interesting thread to me (well, some of it..) as my RS has been scaring me witless on a 2 week tour of Europe with head shakes. It is prone to them at ~46MPH (74KPH?), particularly on overrun but also occasionally while gently accelerating. The first was overtaking a lorry uphill, then along a sweeping left hander as the road continued to curl up the hill - the bike shook its head the whole way, slewing across the lane with the rear also joining in in the boinging action when I let off the throttle. The plot only came back together when it slowed back down to ~40MPH. That night I checked the steering head bearings for notchiness (didn't find any) and clunking front to back, of which there was also none. I clicked the preload up on the rear shock from 2 to max and carried on, the shakes still evident but nowhere near as vicious.

Over a week later I found myself on the B500 in Germany's Black Forest, on a Sunday. This is a sweeping public road very popular with sportsbike riders who needed to be taught a lesson - the K was ridden full force, fully loaded with luggage (full panniers and a hoooge dry bag strapped to the rear of the seat) and again while leant over at about 30 degrees, near the redline in third (obviously this is fantasy!) the thing started to weave and boing again. All very entertaining and no one dared overtake, but it makes you think about what is wrong or lacking. My bike is shod with Continental ContiGo cross plies which seem to be crap, and the rear tyre has a disturbing amount of sideways flex to it if given a sharp kick - I think this really can't be helping things. The talk of trail here makes no sense to me though as my worst head shakes have been under acceleration with luggage, where the rear is squatted and the forks extended for lots of trail. Maybe it is too much? I also have the optional three spoke wheels if they make any difference, running 38PSI in the front and 40PSI at the back. I also have a fork brace.

I would guess that all K100s do this, but it is only noticeable on the RS because of the narrow bars - a little counteraction at the start of the shake kills it outright, with wider bars it would be stopped probably without any thought every time. My favourite suspect for this is flex in the spine frame, the whole lot seems a bit wobbly when the going gets really tough.. That the K1100 has extra bracing between head stock and spine suggests there may be some truth to this. I also suspected harmonics with the engine vibrations too but it seems to happen at the same speed in any gear, though possibly worst in top. So yeah.. If I find out what it is I will let you all know. Pretty fucking dangerous though.


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1989 K100RS SE ABS 8v  VIN: 0149214
Others: 1.5 x Honda CBX250RS-E, '94 CB250, '95 TRX850, '16 Z250SL
http://justbikethings.blogspot.co.uk/
    

128Back to top Go down   K100RS Steering wobble: All potentials - Page 3 Empty Re: K100RS Steering wobble: All potentials on Tue May 27, 2014 11:07 am

RicK G

RicK G
VIP
VIP
Check the swinging arm bearings for play and also the rear wheel for play in relation to the drive. Other than that I would strongly suspect a crap rear tyre. Maybe put a few extra pounds in it and try.


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"Man sacrifices his health in order to make money.
Then he sacrifices money to recuperate his health.
And then he is so anxious about the future that he does not enjoy the present; the result being that he does not live in the present or the future; he lives as if he is never going to die, and then dies having never really lived."   Dalai Lama


Bikes 1993 K1100 LT, 1998 K1100 LT, 1993 K75 RT, 1996 K75RT, 1986 K75 GS, 1979 Z1300 Kawasaki X 2 for now
    

129Back to top Go down   K100RS Steering wobble: All potentials - Page 3 Empty Re: K100RS Steering wobble: All potentials on Thu May 29, 2014 7:13 pm

Snod Blatter

Snod Blatter
Life time member
Life time member
The rain finally stopped for a few moments today so I went and had a quick check - there is no sideways or anything-way play at the wheel, so chassis bearings seem to be fine. The rear tyre however was down at ~35 PSI so I have pumped it up to an almost explosive 44 PSI and also topped up the front too, all I need now is a dry enough day to do some properly forceful testing.

I don't know what the maximum pressure is that I can put into the tyre but it gives maximum load at 42 PSI - does that count? Either way a couple of PSI is well within the inaccuracy of different gauges anyway!


__________________________________________________
1989 K100RS SE ABS 8v  VIN: 0149214
Others: 1.5 x Honda CBX250RS-E, '94 CB250, '95 TRX850, '16 Z250SL
http://justbikethings.blogspot.co.uk/
    

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