I just went on my first longish ride on my 1985 K100RS. We were gone 8 days all over central and southern BC. It was a blast. The only annoying thing was the numb hands. I have read lot's of articles and want to try to add poly-urethane filler and lead shot to the bars. Is there any danger in cutting the ends out of the heated grips, or will I cut through heat wires.
Other than that the trip was a blast and the bike never missed a beat. We had one bout with heavy rain and as usual you don't put on your rain gear till it's too late. I didn't put mine on at all and after one hour of heavy rain I was surprised how unaffected I was. I just tucked a little tighter behind my Aeroflow and kept my legs as close in as I could and when we stopped my pants were completely dry and my boots were a tiny bit wet but only on the outside. Not the case with my friend on the Triumph Daytona, he was soaked. But we laughed our heads of together. Good times
Thanks in advance. Someone always answers.
Doug

Although I didn't know in the first place when I bought my RS (but was pointed out by people in this forum), I have the Basic handle bar on mine. Much more comfy especially when playing around with the tilt. That's way better than anything you can do to your original RS bar. Then I put weights (600 g each) on the ends, which BMW didn't do at that time, since they already put everything else in rubber. The weights catch heaps of the vibrations (you can see that with the naked eye) and help keeping the hands from getting numb.

Doug,

Are you trying to tell us that the K100 vibrates more than you 1975 XS650?

According to this BMW parts break down, the bar end weight can be installed with the heated grips. The wire is coming from the front of the grip.

dschuetze wrote: The only annoying thing was the numb hands. I have read lot's of articles and want to try to add poly-urethane filler and lead shot to the bars. Is there any danger in cutting the ends out of the heated grips, or will I cut through heat wires.

Doug,

There is a slight danger of cutting the wires on the ends of the grips so be careful. The heater lead travels through the grip as illustrated above and does a 180 degree bent at the end of the grip. The lead is soldered to the heater wire which is wrapped around and bonded to a plastic tube. The grip rubber is a tight fit over the tube. If you slice into the grip rubber too close to the plastic tube you will cut through the heater lead at the 180 degree bend. It will be possible to repair the damage but it requires fine soldering equipment and skills. I know because I helped a friend repair his heated grips.

I commisurate with your numb hands syndrome. I had the same problem with my RS. When I converted the bike to an RT, the problem disappeared because:

1. the RT bars are longer (different vibration mode)
   
2. the barend weights dampened the vibration
   
3. I had replaced my BMW grips with softer Pro Grips.
   

One solution instead of lead shot / polyurethane is to try softer, better gips. The Pro Grip 699 / 713 models fit the RS bars and it is easy to replace the existing grips. You carefully slice through the grips with a utility knife being very, very careful not to slice all the way through and damage the heater wires which are wrapped around the plastic tube. Then pull off the rubbers and install the new grips. Use dishwashing soap as a lubricant.

I wrote up a tutorial on changing the heated grips on a K100. It's in the tutorial section of this site.

If you go the route of filling the RS bars with some sort of material, then you commit yourself along the path that you must destroy the heated grips anytime in the future that the grips must be removed. The wires will be trapped inside the bars and become non-removable. Furthermore, you eliminate the possiblity of fishing new wires through the bars because there will not be any way to remove the polyurethane foam from the inside of the bars and the wire will be permanently trapped within the foam. I contemplated the same thing with my RS and ultimately rejected the idea. If you plan never to remove the grips, then your plan might dampen the vibrations.

If you add bar end weights to the existing grips, you will have to fish out the wires from inside the bar because the heater leads must be threaded through the barends. This is evident if you examine the diagram above. You can't fit the barend on the throttle side any other way; you will trap the heater lead and won't be able to twist the throttle. This operation means you will have to remove the connector from the end of the heater leads under the tank and replace it later when the barends have been installed and the wires re-threaded through the bars. It's not rocket science but it is a bit of an operation to complete.

Good luck.

Before you start with the mods, have you considered that you may have a touch of Carpel Tunnel syndrome? I thought that the vibration was causing numbness in my hands before I found out.
If you are over 50, your hands go numb especially at the start of the day and the numbness only affects the thumb, forefinger and half of the middle finger then its likely thats what the problem is. Its the action of gripping the bars rather than the vibration that causes the problem. It is curable with a minor operation if it becomes a real problem.
If it is vibration causing the problem you could try a pair of motorcycle gloves with gel filled pads on the palms. They are quite effective at isolating your hands.

I guess I am saying that my K100 gives me more buzz problems than my old XS 650. I have ridden it up and down Vancouver Island a bunch of times bet never noticed the numb hand problem.
It seems one way to know if it's Carpel Tunnel would be to swap bikes with a younger guy who doesn't have this problem with his bike and see if my ride gives him a buzz.
I think I'll take Robmack's advice and not fill the bars with goop. It makes sense. I might try lead shot and see if it helps. I know I won't quit riding because of it that's for sure.
Thanks again, Doug

The Swedish police force where delighted when they where getting the new K 100 RT instead of their old R 75s.
After a while there was so much complaining from the officers of hand and feet getting numb that the health department took the bikes out of service.
The K 75 RT was then issued and served well for about twenty years.
Interestingly though is that both the K 100 RT and RS sold a lot better than the K 75 to private customers.
My RS does vibrate at around 90-100 Km/h,I won`t deny it.
I´ve found out that throttle butterfly synchronisation can make a lot of difference.
Well padded gloves helps too.
Cheers,Wikur!

throttlemeister.com

These, in the heavyweight version, saved me from the electric motor buzz that my K100RS once transmitted to my hands.

Try a set of those foam grips. I have them on my K100 and they really cut down the vibration. Only last a couple of seasons, but at $5 a pair?.....

Just chiming in (because i can), i have done many long journeys on my k100rs and haven't felt numb hands. One thing that has been a huge help is the throtle lock bolt. BMW did that one right. I can cruise for hours and my hands are just resting on the handlebars. Glad to hear someone else doing vancouver island. Have you done the new paved Mesachi - Port Renfrew run yet. WOW!

Note that the Throttlemeister barend 'weights' are primarily a throttle tensioner as well. The left's static, but the right hand side twists in or out towards the throttle tube which varies tension thus alleviating fatigue. They work a charm.

As I rode along the Hume highway recently from the border of Victoria up towards Sydney in weather ranging from near-freezing fog and 2c degrees, to bright sunshine and a top of 15c Aussie Wintertime degrees, I got thinking about the issue of vibration, buzzy bikes, numb hands and age accompanied tenderness. As you all likely know, buzz is caused by vibration, which is mechanical imbalance of varying degrees. The four-cylinder version of these K bikes we adore have more than their fair share of inherent imbalance, some of which can be rectified by a proper state of tune, such as throttle body sync, valve clearance settings, ignition timing, & etc.

I rode along at Motorway speeds ranging from the typical heavy traffic, sub-100 kph on up to 140 when the road was open and the urge took me, to the F3 Expressway rush of 130 to 140 kph (traffic flows like this North of Sydney regularly). The bike was smooth and relatively buzz-free. It has its moments at about 3300 rpm and a bit more at 4500 rpm. The heavy bar end weights I whacked a coupla months back do a good job at managing some of the vibes. But there's always something more.

My prior time on this bike was done on Bridgestone S11 tyres and then the roadtrip up North last month was done on a set of Pirellis that were not exactly balanced properly, and the accompanying vibrations made the trip uncomfortable at times - the original set of Pirelli tyres weren't fitted by my usual dealer. Once back at home I had my original tyre fitter spoon a new set on, and properly balance them using a dynamic (spin) balancer instead of the usual static balance technique, or worse, no balance at all. It makes a huge difference. My right hand which felt more than a bit tingly at day's end on prior rides, but now is as good as new. I'm just off the bike for the day and managed about 700 drama and vibe-free kilometres today. This has been the case for all of this near two week ride.

Tyre imbalance: just something else to consider regarding additional causes for numb-feeling hands.

TWB makes a very important point, a number of people say one does not need to balance bike tyres at all which I believe is rubbish. A lot more say only static balancing is required and I feel that is very questionable since the width especially of the back wheel gives ample opportunity for both static and dynamic imbalance. The front wheel also can be out both ways.

If one looks at it simply and asks is tyre imbalance a good thing or a bad thing? I firmly believe it is a bad thing and doing as TWB has done getting the wheels both statically and dynamically balanced logically has got to be beneficial. TWB has conclusively proved that is correct. I shall definitely get mine done, although it seems hard to find people who can dynamically balance bike tyre/wheel combinations over here.
Regards,
K-BIKE

Any time that I replace a tire, it is dynamically balanced. I believe that here in Halifax all the major bike dealers have a dynamic tire balancer.
You can always try the dynabeads if nobody has the equipment to dynamically check your wheels.

A bit of research has shown so far only one bike tyre dealer has a dynamic balancer that will take bike wheels, all the rest have static balancers. I am going to trawl through the motor tyre companies now.
Regards,
K-BIKE

I realise this thread is now a few months old - but can anyone else remember that bach in the 80's one firm used to sell a very strong "bungy" device for handlebar damping? From memory, it was a fairly short strong elastic that was stretched tight through the bar - and retained either side somehow.

Never tried it - but people reckoned it worked.

Mike