standard forks or leading link ?  is a bit to fast imo , take it easy

Leading Link. More enjoyable slowing down with the sidecar rig yes but could the old two wheelers perform well at interstate speeds?

i have never had a problem they are a very very good bike , i did have a guzzi outfit for a while but now have 3 wheelers (morgan) and bikes , is the fan cutting in ? forgot to ad your k100rs is a 120 mph plus bike . no problem 100 mph all day .

Once you have the coolant system sorted, if there is still too much heat for the rider, it could be that some panels are missing from the fairing. 

I'm not familiar with the RS model, but with RT models there are internal panels above and behind the side vents to direct engine heat out the side vents and away from the tank and rider. There might be a panel between the fairing and forks. On mine I turned it upside down, that resulted in air scoops, reducing the heat. The rear panels were missing on mine. 

My brick sat for years before I got it. On the first ride, the heat on my legs was unbearable, and it was winter, I thought if this is the way it is, I'll be selling it. Maybe the heat was due to its first ride after many years, maybe the missing rear panels, or maybe the missing air scoops, dunno but the problem is gone now.

Thanks for the feedback. I thought the K's were good at speed traveling bikes. Adding the sidecar puts a bit of a strain on the bike but these motors seem to be up to the task. I guess I have to look into the science of the K-Bike fairing and panels. I know some who remove the lowers to help improve cooling but I'm not sold on that.

A fair bit of heat comes from the fuel tank.  In hotter climates the fuel can get hot enough to boil.  The source of the problem seems to be the fuel pressure regulator that is mounted right behind the radiator. 

There are two fixes, the first is to add some sort of a fuel cooler, and the second which is probably a lot easier would be to move the fuel pressure regulator from it's little corner of hell out from behind the radiator to a location above the fuel rail out of the main airflow from the radiator.

Here is how Bert(Crazy Frog) did it on his bike:https://www.k100-forum.com/t15210-relocating-the-fuel-pressure-regulator

The only thing I would do different from CF's arrangement would be to find the space to get the body of the regulator further forward to avoid the hot air from the radiator.  I would also make the fuel lines as short as possible but still allow for moving the tank back far enough to access the coolant filler.

Fortunately fuel problems did not haunt me but thank you for the tip

You should have heat insulation on the underside of the tank, stuck on with a reflective foil finish. There is also a plastic/rubber baffle that the tank sits on, you should see it at the headstock end of the tank. Also the fairing baffles mentioned are important.

I have had less of these issues using Motul 20W50 3000 mineral oil and use it in all my Ks.

spat wrote:I guess I have to look into the science of the K-Bike fairing and panels.

To read something about the mechanics of Brick heat management, click this link, agree, then read the heat management document in the Frame section.

I had good success in insulating the fuel lines under the tank using foam pipe insulation. After I did this, I no longer had the gas tank boiling. I used a beaded pad, cutting down a full size back rest beaded seat overlay. I also have a lamb's wool pad that works very well.

Glenn

Ive spent the last 16 years and many kms (150,000 maybe) on a K100RS sidecar. The last 10 or so with much EML stuff retrofitted, which stiffened it and made it a much better running and handling outfit.

It was a great travelling rig, even did a few 1000km days without any discomfort. It started out as pure RS setup but was a better bike with RT handlebars fitted, both for the ride position and making the steering effort easier on the shoulders. It had 15" wheels front and rear, running a 165-15 rear and a 130/90-15 bike tyre up front. 135 rears wore out too quick and would spin up sometimes on wet twisty roads. After running all sorts of tyres up front the bike tyre was the best compromise, a 145/65-15 front car tyre was fabulous but was very difficult to get it seated and difficult to remove, wasn't worth the grief.

Most of the RS has now gone to Woz (Wollongong)

 Hi Spat and welcome here!
I'm riding a K100RT (with RS fairing) with an EML GT2001.
Have the RT steer mounted for comfortable handling.

About your heat-problem: don't forget that the wider front fender and wheel take a lot of the cooling wind away from the front / radiator! That said: try to optimize the wind-flow trough the radiator with the internal parts of the fairing mounted (mentioned eslewhere in this thread). Also the insulation of the fuellines is a good point.

We took the rig for a 10-day journey to Poland in summer 2019. All-in-all about 5000 kilometers, in very warm conditions. Most of the time we drove country-roads, on average about 80-90 km/h (60 miles/h), a very pleasant drive!
On the way back we had to hurry home and took the German autobahn. The speed there was about 130 -140 km/h, still in warm (hot...) conditions. Never had an issue with the cooling system though... (My left upper leg sometimes was nearly cooked, but that was all.)

Enjoy your rig!

Greetings from the Netherlands
Jos