Wondering if there are different temp thermos for these bikes. Whats stock and what is available?

Why would you want to run a different thermostat then the one the bike was designed to run with?

Yeah, K's get nearly unbearable hot in summer stop-n-go traffic. 

Instead of thermostats, consider upgrading your rad fan. It's easy and the replacement is a galaxy better than the OEM of thirty years ago. 

https://www.k100-forum.com/t8728-overheating-88-k100rs. Scroll down for the words 'Spal puller fan.'

Kyle10 wrote:Yeah, K's get nearly unbearable hot in summer stop-n-go traffic. 

Instead of thermostats, consider upgrading your rad fan. It's easy and the replacement is a galaxy better than the OEM of thirty years ago. 

https://www.k100-forum.com/t8728-overheating-88-k100rs. Scroll down for the words 'Spal puller fan.'

Good advice, I was going to do that actually if it is warranted. Seems to be eh?

duck wrote:Why would you want to run a different thermostat then the one the bike was designed to run with?

Due to what Kyle says after your response....exactly that mate....

When you are riding the airflow and the thermostat control the heat.

When you are stopped and the engine heats up the rad fluid, the fan kicks in to cool it down.

I think more productive mod would be to add a fan switch.

duck wrote:When you are riding the airflow and the thermostat control the heat.

When you are stopped and the engine heats up the rad fluid, the fan kicks in to cool it down.

I think more productive mod would be to add a fan switch.

Even easier, which I was going to do as well. I think I'll add the switch and see how that goes before messing round with the fan.

Or add more insulation under the tank.

duck wrote:Or add more insulation under the tank.

Where can I get that insul, and what kind is it?

You can get it at Home Depot.  Goes by the name "Reflectix".

SniperX wrote:

duck wrote:Why would you want to run a different thermostat then the one the bike was designed to run with?

Due to what Kyle says after your response....exactly that mate....

A different thermostat won't make the engine run cooler in hot conditions. Its function is only to restrict coolant flow when the engine is cold so that it reaches operating temp quicker. Once at op. temp the thermostat is fully open. It can't provide more coolant flow than that.

Ensuring your thermostat is working properly would be a good start.
Air leaks will lean the fuel mix making the engine run hotter.
Adding insulation under the tank will help to keep the fuel temp down and prevent some of the heat flowing up to the rider.

To make your cooling system more effective you need to make the radiator surface area larger and make the air flow across that area better. The early K100 83 and 84 had a 3 row radiator where the later models have a 2 row. Try to get one of those, they are still around and many are in good condition if the right coolant has always been used.
I have a 3 row on my K1100 and it still gets hot very quickly on 40°C plus days but when the fan comes on it cools much quicker. When the hot days do occur I run my standard fan all the time when in heavy traffic as that prevents the engine getting to the overheat situation when the fan will cut in. I have found that the more the standard fan works the less likely you are to have trouble with it. I will also replace the fan with a much better more modern unit if it does fail.
This is a 3 row bit pricey but http://www.ebay.com/itm/BMW-84-97-3Bank-RADIATOR-Intercooler-K100RS-K100LT-K1100RS-K1-K1100LT-K75S-K75RT-/380824402272?hash=item58aae73960:g:JVIAAMXQlgtS4AOH&vxp=mtr
I think this is also a 3 row but hard to tell http://www.ebay.com/itm/BMW-Radiator-K100-BEHR-/370786911333?hash=item56549f4465:g:iHQAAMXQlUNRVOKx&vxp=mtr