Johnnymannen
Husqvarna
AA Class
I have a WR 300 that i use on the street also with super moto wheels. My bike is also sensitive for wobbling, and i think the rteason for this is that the forkangle is made for 21" rims that makes the front of the bike stay much higher and therefore increase the forkangle. When you put on a 17" wheel the front of the bike is leaning more "forward and therefore decreasing the forkangle which leads to more instability. I think one solution would be to use a shorter rear spring to increase the forkangle again. Also the front fender is very important to change to a super moto one because the airflow makes it even worse.
Johnny
Johnny