On the way to see the races I noticed that the bike started to have the shakes at around 110 - 115 km/h. This was a new issue as it never happened with the Sahara 3s. The TKC 80s have now done around 2000 kms, but they still have plenty of thread left in my opinion.
The head shake on the 690 is an interesting phenomena as some people suffer from it and some people don't. It's usually "solved" by adjusting the suspension, adding a steering damper, changing tires etc. None of which seem to be the end all solution to the problem.
As I didn't have any tools or time to mess with the suspension I decided to check the tire pressures on the nearest gas station. The front had 1.2 bars and I decided to up the pressures (to 1.8) on the front first to see what happens.
Interestingly the head shake disappeared and the bike became instantly less twitchy at high speeds! You might want to try messing with the tire pressures first before buying expensive dampers etc.
ABOUT HEAD SHAKE
Reading the reports around the net from people experiencing head shake blames the problem on several different things or a combination of them. Which ones you believe in is up to you.
1. Bad tires: some tires when worn will start to induce head shake and some seem to do it even when new.
2. Incorrect tire pressures for high speeds. Raising front pressure made a big difference for me.
3. Suspension not adjusted correctly (preload, sag etc.)
4. The amount of load (luggage) on the bike and how it's placed. Mine seems more stable the more suff I pack on. This is ofcourse related to suspension setting.
5. The bike's steering geometry in general. (I don't agree as the problem is not with ALL the 690 Es)
6. Wheels not balanced correctly
7. Wheels not aligned correctly (rear especially)
8. Heavy inner tubes. I personally find that the heavy Michelin UHD tubes feel a lot different than regular thin ones and might very well be a contributing factor to the problem.
Many people attempt to fix the problem by installing a steering damper which in my opinion only mask the original problem and is not a proper fix.