Hi, I haven't put lots of miles into my K100RS, mainly because I find the handling somewhat alarming on less than perfect surfaces. I'm running Bridgestone BT45's, new rear, nearly new front at the recommended 32/36psi and softest solo pre-load. I'm 14 stone so about average, and the bike runs naked. The tyres were professionally fitted and balanced.

At the first sign of a white line the back end gets seriously out of line. I took my wife on the back and bumped the rear pressure up to 39psi and the rear shock to the hardest setting and the bike became much more forgiving, without being totally confidence inspiring. I'm wondering whether running it at 39psi solo and pre-load on the middle setting would make it a nicer ride, but I don't want to square the tyres off prematurely if that's too hard.

Front shocks seem fine and swingarm is okay so far as I know, it just passed an MOT. Any advice welcome, thanks.

I have found that the steering head bearings will cause that sort of thing if lose or worn and notchy and the Ks are fussy about the tyres and pressures. Check the rear shockie for damping and bounce.

Welcome too.

I am using the BT45 for a few years and find them great.

On both Ks I had to do head bearings and it made a very significant difference.

I am probably opening a can of worms here but I weigh in under 12 stone and even running the bike naked I run the tyres quite a bit harder. I use about 39 rear and go about 42/43 if I have full panniers/topbox. I also use at least 36 on the front. Rear shock stays on full load all the time.
 
Its worth experimenting on the pressures to find what works best- as RickG says they are sensitive to tyres but once you find what works for you then they are very sure footed. The rear shocks are not the most durable either so keep an eye on it.

Thanks for the advice. The previous owner was a mechanic and said he did the head bearings and forks every year, so it will something to keep an eye on. I'll experiment with tyre pressures and pre-load. It's a big bike running on fairly narrow rubber by modern standards, so I guess the air pocket has to be just so for the weight carried. Cheers.

strongly agree with rick ......check - sus out the rear shock ...they do tend to go wayward and get all sloppy

causing all sorts of weird handling situations

you really wont know how bad it is ...until you swap to a newer unit and feel the difference first hand

by pushing up the pressures you are just restricting the flex of the driveline ...and lessening the impact of a poor shock ...till you get to a good speed ...then it all falls in a great big heap of poo

borrow one if you can, to test the theory ...

also highly recommended changing the damping fluid in the front forks ...it is really amazing how bad it could be... till you change it ....it is often overlooked ...and unless you can find evidence of a forkoil change in the last 3 years ...just do it !
test for front fork sag of the springs also
there are recommendations for the amount of expected spring tension ...which aren't hard to test

hope it gets better soon

good luck !!

Ok, I've had rear shock, tyres, swingarm and headstock checked by a BMW specialist, and all are fine. It seems my experience is down to the RS's narrow bars, a weighty bike and plenty of power through some narrowish rubber. Short of putting in some serious gym time, or swapping for the RT's handlebars, it seems the handling is what it is and I'll have to learn to live with it.

They should handle very well, if you are having problems then it can be sorted. Firstly slacken off the bolts holding the front axle, 2 on the bottom of each fork and 1 on the end of the left end of the axle.   Hold the front brake on and pump the front end. Tighten the bolt on the end first and pump again. This will make sure the forks and sliders aren't binding.. due to the legs not being parallel. Tighten the other 4 bolts.
Take it for a ride and report back.

RicK G wrote:They should handle very well, if you are having problems then it can be sorted. Firstly slacken off the bolts holding the front axle, 2 on the bottom of each fork and 1 on the end of the left end of the axle.   Hold the front brake on and pump the front end. Tighten the bolt on the end first and pump again. This will make sure the forks and sliders aren't binding.. due to the legs not being parallel. Tighten the other 4 bolts.
Take it for a ride and report back.

Thanks for the advice. The bike has been comprehensively checked over. I think the problem is partly with me and partly with the design. Narrow handlebars have little leverage which leads to me over correcting, especially on imperfect road surfaces, which in turn makes me tense up aggravating the problem. I've had quite a few bikes and the K100RS is the only one that didn't corner instinctively but has to be "thought" through a bend. More experienced BMW riders who've ridden it seem to think "they all do that, sir". Next step is to try heavier fork oil but I don't think it'll feel right without wider bars, and it would be easier to swap for an RT.

Rick is right about the handling - they do handle well but yes, it needs thinking out and positive input. Quite a few of use have boot soles with scrape marks on to prove it. It can be a bit of a shock coming from modern lightweight Japanese bikes. After riding LFB continuously for many months I was forced back onto my 600 Bandit. On that run I think I undershot every corner on my daily 50-mile commute because of the weight difference - !

Surprisingly, I find tyre pressures to be a bit critical. I run 34 front and 38-40 at the rear, but I also have progressive springs in the front and a RamShok at the rear. Those two mods transformed it from a slug (when I got it) to a bike that's capable of at least startling modern Japanese machinery.


Oh yes - check the rear shock is the right way up. The adjusting collar should be at the top, not at the bottom where you'd expect to find it.

sniffy   (post #1) wrote:Hi, I haven't put lots of miles into my K100RS, mainly because I find the handling somewhat alarming on less than perfect surfaces. I'm running Bridgestone BT45's, new rear, nearly new front at the recommended 32/36psi and softest solo pre-load. I'm 14 stone so about average, and the bike runs naked. The tyres were professionally fitted and balanced.

At the first sign of a white line the back end gets seriously out of line. I took my wife on the back and bumped the rear pressure up to 39psi and the rear shock to the hardest setting and the bike became much more forgiving, without being totally confidence inspiring. I'm wondering whether running it at 39psi solo and pre-load on the middle setting would make it a nicer ride, but I don't want to square the tyres off prematurely if that's too hard.

Front shocks seem fine and swingarm is okay so far as I know, it just passed an MOT. Any advice welcome, thanks.

JMO but you might get better performance out of your tyres if you keep the pressures up in the high 30's. Low 30's will prematurely wear the treads and promote scalloping. In my experience when the tyre is badly scalloped it doesn't track properly giving you dodgey performance over road markings and tar patches. At high speed a low oscillating wobble and under-steering. Not really a confidence building experience.
My front is always within 2 psi of the rear and that's at 40 ±1psi. I'm around 73kg (11½st)

Also, using an 'active' riding style can help if you are not already. Leaning forward and into the corner, especially at lower speeds will help get the weight over smoothly. Keep the arms bent. Some here have commented on the improvement in handling going from RS to RT bars due to the fact that they aren't leaning rigid on the bars with a more upright position with RT bars. Its all down to personal preference but as we get older some of us are finding our elbows are not up to it anyway.

Mine is very wayward going over white lines and road imperfections, made worse with worn tyres. I am also running the standard 36 PSI in the front and 42 PSI at the back, the more in the rear tyre the better but I can't face the risk of it exploding with even more in there! I am an apparently lightweight 70kg/11 stone, to boot.

I have put a Michelin Pilot Activ on the front of mine which has seemed to help a lot, the previous Conti Gos and ME33 front/Roadrider rear combos were okay when new but quickly became challenging to live with in regards to white lines, and ridiculous wallowing/head shakes as they wore out.

My rear shock is low on miles but quite old, must be 20 by now. The forks have progressive springs but they're likely not right for the S forks mine has, and there is a slight notch in the head bearings which can only be felt with the front wheel removed so there is less weight to turn around - the MOT man didn't notice anything. I have a funny feeling they're all like this.. At least the RS's.

I'm a little surprised to read people saying that the Japanese bikes handle better than the K-bikes.  In my experience, my K11 feels much more natural in turns, even low speed maneuvering than the KZ1000 I was riding.  However, I have to admit, when the front tire is under inflated, it handles like a tank.  For me, the factory recommended 32/36 front/rear riding solo is not optimal.  I find 36-38 in the front and 38-40 in the back gives me the best handling experience.  Just my two cents, FWIW.

Cheers,
Nolo

Thanks again for the input. The variety of pressures riders are running, and how far they veer from manufacturer's recommendations and each other, is surprising. I'll experiment with front tyre inflation tomorrow.

I see now your's is a 16v so is using radial tyres. Game change, I run RS wheels on my LT and run 40 front and 44/46 rear otherwise it is an absolute pig.  I run pilot road 2s and get 22/23k from the rear and more from the front but change both together for the sake of convenience.

TIP put the model and VIN of your bike in the signature line and that saves us having to find out and you typing it each time.

RicK G wrote:I see now your's is a 16v so is using radial tyres. Game change, I run RS wheels on my LT and run 40 front and 44/46 rear otherwise it is an absolute pig.  I run pilot road 2s and get 22/23k from the rear and more from the front but change both together for the sake of convenience.

TIP put the model and VIN of your bike in the signature line and that saves us having to find out and you typing it each time.

It's an 8-valve 1988 RS with Bridgestone BT45 cross ply tyres, not radials.

Just took the bike for a spin on gravelly back roads. Tyres at 35/39 psi handling much improved. I suspect my pressure gauge has been optimistic and I've been running low. Will keep experimenting.

sniffy wrote:

RicK G wrote:I see now your's is a 16v so is using radial tyres. Game change, I run RS wheels on my LT and run 40 front and 44/46 rear otherwise it is an absolute pig.  I run pilot road 2s and get 22/23k from the rear and more from the front but change both together for the sake of convenience.

TIP put the model and VIN of your bike in the signature line and that saves us having to find out and you typing it each time.

It's an 8-valve 1988 RS with Bridgestone BT45 cross ply tyres, not radials.

My apologies but I was going on your initial post in your introduction.
"I got myself a 4 valve K100 RS last year and have been enjoying its charms and challenges! I'm your typical born again biker having used a bike for all transport, including a 50+ mile commute for many years and all seasons. Marriage and children meant a lay off and the K is my toe back in the game"

RicK G wrote:

sniffy wrote:

RicK G wrote:I see now your's is a 16v so is using radial tyres. Game change, I run RS wheels on my LT and run 40 front and 44/46 rear otherwise it is an absolute pig.  I run pilot road 2s and get 22/23k from the rear and more from the front but change both together for the sake of convenience.

TIP put the model and VIN of your bike in the signature line and that saves us having to find out and you typing it each time.

It's an 8-valve 1988 RS with Bridgestone BT45 cross ply tyres, not radials.

My apologies but I was going on your initial post in your introduction.
"I got myself a 4 valve K100 RS last year and have been enjoying its charms and challenges! I'm your typical born again biker having used a bike for all transport, including a 50+ mile commute for many years and all seasons. Marriage and children meant a lay off and the K is my toe back in the game"

No, it's my fault, I'm not up to speed on the jargon. The 16v is referred to as the 4-valve I believe. Mine is the old 2-valve per pot variety.

Dai wrote:
Oh yes - check the rear shock is the right way up. The adjusting collar should be at the top, not at the bottom where you'd expect to find it.

The adjusting collar on mine is at the bottom. Maybe this is the light bulb moment!

It's easy to put the adjusting collar at the bottom because it sort of looks right. When they are upsidedown all the oil just foams with very little damping in either direction.
Now you should find out how a K really feels.

RicK G wrote:It's easy to put the adjusting collar at the bottom because it sort of looks right. When they are upsidedown all the oil just foams with very little damping in either direction.
Now you should find out how a K really feels.

The previous owner had the bike a long time and a lot of miles. I can hardly believe he rode with the rear shock the wrong way up all that time.

I have met a few people who don't even ridw well enough to realize that the bike is an absolute pig. One in particular that comes to mind bought an MV Augusta with an insurance payout and he was so slow we christened him Bandit because he held everyone up. It was a real strawberries to pigs effort.

sniffy wrote:The previous owner had the bike a long time and a lot of miles. I can hardly believe he rode with the rear shock the wrong way up all that time.

But for the power of this forum you may have done the same. Credit to you for noticing something was not right. Often is not so much the wisdom found here but the conversations we have that bring it out.
Here's hoping you'll have something positive to report back.

Kaptain Holister wrote:

sniffy wrote:The previous owner had the bike a long time and a lot of miles. I can hardly believe he rode with the rear shock the wrong way up all that time.

But for the power of this forum you may have done the same. Credit to you for noticing something was not right. Often is not so much the wisdom found here but the conversations we have that bring it out.
Here's hoping you'll have something positive to report back.

Being unfamiliar with the Ks, the usual tyres, fork, swingarm, shock scenario seemed to exhaust the possibilities. Who'd guess the unit would be ar*e up? Looking at my Haynes and internet pics after Dai's suggestion the thing seemed too weird to be true. But there it is. Just when you think you've seen everything...

One last thing on this: SUPPORT THE BACK WHEEL BEFORE TAKING THE SHOCK OFF. Yeah, caps because it's important. If you allow the swingarm and wheel to drop you stand the possibility of putting a big dent in the back of the gearbox (both Charlie99 and I have one) and also ripping the clutch boot. There's an outside chance of ripping the swingarm boot too but that's pretty tough.

Dai wrote:One last thing on this: SUPPORT THE BACK WHEEL BEFORE TAKING THE SHOCK OFF. Yeah, caps because it's important. If you allow the swingarm and wheel to drop you stand the possibility of putting a big dent in the back of the gearbox (both Charlie99 and I have one) and also ripping the clutch boot. There's an outside chance of ripping the swingarm boot too but that's pretty tough.

Dai, do you mean support the wheel, or support the gap occupied by the missing shock? I was going to do the job this afternoon and jamb something suitable in the space. Haven't had a hands on look at the problem yet so any advice gratefully received.

Now I'm really confused. Before steaming in with the rear shock inversion, I thought I'd check Chris Harris's YouTube site. The K100 he's working on definitely shows the rear unit in the same orientation as mine, with the adjustment collar at the bottom.

Are there any exemptions to the collar at the top rule before I get my hands dirty? Mine currently has the chrome piston at the top and the black chamber and collar at the bottom, as does the bike in Chris Harris's video.

sniffy wrote:Now I'm really confused. Before steaming in with the rear shock inversion, I thought I'd check Chris Harris's YouTube site. The K100 he's working on definitely shows the rear unit in the same orientation as mine, with the adjustment collar at the bottom.

Are there any exemptions to the collar at the top rule before I get my hands dirty? Mine currently has the chrome piston at the top and the black chamber and collar at the bottom, as does the bike in Chris Harris's video.

There seem to be....
Mine is a K1100, and the shock has the adjusting collar at the bottom.  Checking  a few things, I noticed that this shock has more preload adjustments than a K100 one. and it also has a rebound adjuster at the top, which fits a flat screwdriver and adjusts hard or soft rebound.. It shows a circular arrow with an "S" and "H" at either end, for Soft and Hard. The letter S is definitely the right way up when the shock has the collar at the bottom, i.e. the font of the S makes it obvious - with the top curve of the letter being smaller than the bottom (if I am explaining myself correctly).

So it would appear that some BMW K shocks definitely have the adjustment collar at the bottom.

Corkboy wrote:


There seem to be....
Mine is a K1100, and the shock has the adjusting collar at the bottom.  Checking  a few things, I noticed that this shock has more preload adjustments than a K100 one. and it also has a rebound adjuster at the top, which fits a flat screwdriver and adjusts hard or soft rebound.. It shows a circular arrow with an "S" and "H" at either end, for Soft and Hard. The letter S is definitely the right way up when the shock has the collar at the bottom, i.e. the font of the S makes it obvious - with the top curve of the letter being smaller than the bottom (if I am explaining myself correctly).

So it would appear that some BMW K shocks definitely have the adjustment collar at the bottom.

That's interesting. I can't see any rebound adjuster or S and H marks, just a chrome collar with the usual three preload positions. The top of the piston chamber has the words "Do Not Open" and the same in German. That suggests it's a BMW unit rather than an aftermarket shock, but I have nothing to compare it to. The words are facing upwards, so I'm inclined to believe it's fitted the right way but if anyone can look at theirs for comparison I'd appreciate it.

Yours definitely sounds like a k100 OEM shock (that has 3 positions, the K1100 has 5, and the rebound adjuster).

Someone with a K100 shock will have to chime in with the right way up.
But on looking at images on t'interweb, it looks like the adjusting collar, on the K100 is on top in all of them.

Corkboy wrote:Yours definitely sounds like a k100 OEM shock (that has 3 positions, the K1100 has 5, and the rebound adjuster).

Someone with a K100 shock will have to chime in with the right way up.
But on looking at images on t'interweb, it looks like the adjusting collar, on the K100 is on top in all of them.

Thanks Corkboy, it's as I thought. The previous owner kindly went through his old photos, including the ones I bought it from, and the collar is at the top. As it has only been to the garage once for work in the meantime, which would have meant removing the shock, I think we've narrowed down the problem!

K100 shock has the adjuster on the top.....of course down under they may be the other way round......

sniffy wrote:

Dai wrote:One last thing on this: SUPPORT THE BACK WHEEL BEFORE TAKING THE SHOCK OFF. Yeah, caps because it's important. If you allow the swingarm and wheel to drop you stand the possibility of putting a big dent in the back of the gearbox (both Charlie99 and I have one) and also ripping the clutch boot. There's an outside chance of ripping the swingarm boot too but that's pretty tough.

Dai, do you mean support the wheel, or support the gap occupied by the missing shock? I was going to do the job this afternoon and jamb something suitable in the space. Haven't had a hands on look at the problem yet so any advice gratefully received.

If you haven't done it yet - support the wheel. Stick a big block underneath it.

92KK 84WW Olaf wrote:K100 shock has the adjuster on the top.....of course down under they may be the other way round......

Correct Olaf... we antipodeans need to stand on our heads to check that we have it the right way round tho! Thank heavens for gravity aye! What DID we do before we had that stuff? 

This is the stock oem shockie with adjustment clearly at the top. My '89 RT is the same.

The garage haven't had the shock off, so it's all a complete mystery. Oh well, time to spin the spring and see if things improve. Thanks again to everyone for their contributions.