Hi Jakutash
For diagnosing and issue like this, the GS-911 can be used to run an autoscan/read fault codes on your engine ECU, which will display any faults that are detected as either previously present, or currently present. What this means is that in the event that the thermostat is not sending the expected values to your bike's ECU, a fault code will be thrown on your ECU - this can be used to confirm that the problem is in fact the thermostat, and you can proceed to replace it.
The GS-911 also allows reading and logging of real time values - this can be used to check specific values relating to your cooling system, which can also help to identify where exactly the problem is.
Please feel free to let us know if you have any questions.
Kind regards
Ruan