With the lines of a classical sports car--it's the '85 K100 RT. The RT model was the top-of-the-line early K-bike, but after riding this bike for 2 years in "touring" configuration I finally realized it might go faster and handle better by simply lowering the handlebars. This configuration is more comfortable (less noisy) at speed, and handling is much improved. Who knew that lowered handlebars are what the designers intended all along (see post on: K100RT Egronomics). 

Now with the advantage of modern tires and and a few bolt-on modifications this bike is ready to do what it was born to do, sport touring! Oh ya, and did I mention--it's red! 

Figure 1 above; (left) RT handlebars when lowered down look very similar to RS handlebars (right). The clean rear deck of the early '85 RT merges seamlessly with Corbin gunfighter seat. The '85 also has a center stand upgrade to K1100 style, and note the tri-spoke rims (rare) from '93 K75S.


The RT is very similar to the RS in many respects, the only real difference being faring design and rider protection. Otherwise, the engine, brakes, and suspension are all the same, and the two bikes weigh within 10 pounds of each other. The RT does have a lower geared rear end that makes it slightly quicker in the 0-60, and provides more torque for passing, etc. The '85 and earlier K bikes also have 16-tooth splines that are less susceptible to wear.

Figure 2 above; Monolever rear end w/32-11 gears for quicker acceleration. Aluminum parts unpainted in RT style. Footplates from '86 K100.

continued . . .

On the performance front, the early '85 RT has the larger "Euro" cams to which I've bolted-on a set of tuned headers. The aftermarket exhaust weighs about 10lb less than the OEM, and the bike sounds like a motorcycle again. The performance boost kicks in around 5000rpm and she really likes to rev at that point.

Figure 3 above: Tuned SuperTrapp headers end in stubby silencer. The Corbin gunfighter seat is comfortable and low enough to allow this rider (5'10.5") to plant both feet on the ground.

The handling component of the bike is improved by switching to 3-spoke rims mounted with radial tires. This bike features new Avon Storm 2 Ultra Sport 110/80R18 on the front and Azaro AV46 140/80/R17 at the rear. Radial tires improve ride quality because they flex under load. Radials also have a larger footprint and maintain contact with the road, resulting in better traction and handling.

The rear suspension remains stock, while the front forks use 330cc of 10w fork oil. Brakes remain stock, except for the use of sintered metal pads in front. The sintered pads improve performance and provide a more solid braking feel.

Figure 4 above: Tri-spoke rims with Avon radial tires improve ride quality (also see Figure 2). Front disk mounts and forks painted black in the '86 style. Front and rear DOT reflectors removed for the "Euro-style" look. Unobtrusive rubber plugs seal-off faring safety bar mount holes.

It's important to mount the windscreen properly or it can become problematic. After a long look at OEM assembly drawings I discovered  rubber washers under each of the four front screws that keep the front lip tightly secured and vibration free.

In 1989 BMW introduced wind foils on the lower fairings to help deal with stability and buffeting at high speed. The foils produce low pressure bubbles on either side of the bike that help reduce the effects of wind blast.

Figure 5 above: (left) Vertical air foils on lower fairings stabilize the ride at high speed (also see Figure 4). (right)  Parking lamp painted over in favor of duo-use turn signal/marker lights. Narrow frontage of RT faring slices through the wind. Headlamp (not shown) is a brighter white Philips X-Treme Vision, much superior to the stock halogen bulb. Fork mounted 55w Bosh "rally lights" help locate the curves at night. Aftermarket 'RT' lettering (approx 2cm tall) as the originals are no longer available. (Compare with avatar for before/after appearance.)

Lowering the handlebars on the RT does not involve any changes to wiring or cabling. Early K's were plagued by the "vibes," but by virtue of their longer length the RT bars coupled with end-bar weights are very effective at reducing vibrations. Still, a set of foam grips are installed on longer trips to help reduce fatigue.

Figure 6 above: Symantic heated grips with stock wiring and soft Italian rubber ProGrips. A Ram mirror mount holds a GPS (TomTom) powered by cigarette lighter adapter on top the coil cover (not shown) in the '85 style. LED instrument lights (not shown) for night time visibility. Early style duo-lamp fuel tank warning lights.

About 69,500 original miles on the clock.

Photos taken with i-Phone 5, which doubles as MP3 player while riding.

The 'T' in RT stands for touring. So, it wouldn't be a sport touring bike without panniers, which came standard on the K100RT.

Figure 7 above: (left) Duo-tone panniers modernize the look. (right) Heat reflective tape (not shown) used on the underside of left pannier in lieu of heat shield. Inside the right pannier (not shown) is stored an additional 3.9l fuel reserve bringing total fuel capacity to 6.8gal. (25.9l). 

Let's ride!

looking good there mr valente   , those are nice mods , did achieve what u had hoped for?

happy riding. -o: 

k-rider

Those dropped handlebars intrigue me, will have to try that mod as I do get stiff shoulders after an hour or so. John

Thanks for your kind comments. Yes, the bike has come along nicely. Work has stopped for now as the weather has finally cooperated.

I've been practicing riding technique from a book posted online by Duck "Full Control Riding Manual" and the new position of the handlebars helps immensely. The lean forward position has gotten a number of looks on the road, and is very comfortable (at least on rides of 1hr duration, so far). Now riding on the freeway at speed is a preferred mode of travel, whereas before I dreaded it.

Am also on the verge of recommending radial tires to everyone regardless of rim type because they act as shock absorbers over rough roads. Bias plys tend to jump around, and we have a number of bad roads here in New England due to freeze cracking, not the main highways, mind you, just the back roads. In the curves the handling characteristics of radials are slightly better than bias ply, there's more feedback because the tires grip the road. Radials are definitely more comfortable at speed too because of the wider "plant."  I feel more relaxed and confident than ever before--as Duck has said, it's like a completely new bike. Some people have said that skinny radials are not true radials, I don't know what that means.

Nice job.

Not sure if it matters to you but I'm pretty sure that the side reflectors are a federal requirement.

Hi AJ
Nice one mate. She really looks great and I really like the wheels. Think I'll put that on my list of to-do's.
Are your bars off an RS?

dang ...missed this earlier aj

good write up mate

can I add something ...the fork brace found on different models , I recon does help the front end immensely for that "road plant feel" with conventional bias ply tyres.

possibly the progressive type front spring sets could make a difference to the "conventional "forks as well

but now having the bridge fitted I will go back to and trial a radial on the front  to see what difference it makes to the feel
hope your journey on the rt is as pleasing one as I am having ...

cheers

Kaptain Holister wrote:Hi AJ
Are your bars off an RS?

No, they are not. They look a lot alike, don't they, in this position. These are RT bars lowered to within 10cm of the faring. I've been riding that way all summer. The handling is great and no air blast like before. It's a whole different experience.   

-aj

charlie99 wrote:dang ...missed this earlier aj

. . .
hope your journey on the rt is as pleasing one as I am having ...

cheers

Charlie, I really like your blog too.

Didn't know you're still running a bias ply up front. I'm told front braces, like on the R75, can be a problem with handling at speed. Right now, the radials seem to provide all the response I need, and the bike feels "super" at high speed.

I was doing 70mph passing a car, and the A-hole speed-up (note, there was on-coming traffic!). Well, just a twist of the throttle and I'm up to 95mph and back in control. Same thing goes when a muscle car tries to drag race from a standing stop, or some nut in a SUV wants to pace me around curves. I just don't know what gets into peoples mind's sometimes, I never try challenging a motorcycle when I'm in my car or truck. Go figure?    

So, I'm running with the rear shock on lowest setting and a little less oil in the front shocks for a softer ride. We have a lot of freeze-cracked roads around here, so comfort is a priority. But, handling remains quite firm. It dives a bit on hard braking around town, but that's not a problem (riding 1-up only).

-aj

P.S. I really hope you give the lowered handlebars a try at some point because I know you'd like it a lot.

I like this thread and the K looks great. We don't have a non riding season and ride the Ks through the winter so they don't come off road for spit and polish like this one!! Unless we run more than one.

I have also been looking at riding position but at 5' 8" getting both feet planted at a stop is not an option for me. Was even less so on the LT which had a Comfort seat which I miss. The LT is 92 and the RT 84 so a swap was not on the cards.

I have been looking at a change of bar position but not dropping them. More like risers and bring them back slightly.

But the seat interests me.....at the moment I am planning on having someone local do a job on the seat. Is it an option to build a Comfort seat using the shaped foam from the later seat onto the earlier seat base?

I have Bridgestone BT45 front and rear on original wheels and very happy with them. We do get bad road surfaces here and am thinking maybe go something different. Front is 100/90 18 and rear 130/90 17. Earlier today was looking at main stand as something felt not right recently. Anyway the loadbearing curved part is now cracked so I need a change. I have one on a spares bike which is also K100 or my option is upgrade to K1100.

The spares bike is an RS and is also 84. Was looking at the final drive too which has the RS ratio, since a change would not cost anything should I consider it worth it?