You are talking about a head shake I am guessing? Have you spoken with Nick @ Tekniks since the suspension was done. I am sure if you talk with him he will have a idea or two. I starting noticing years ago at a four day and since that 90% of KTMs have dampers because of the trail and rake they run, this helps them turn well. The down side is that they can then experience headshake. The CRs of the late 80s to mid 90s were like that. Fit a damper I reckon, I personally would own a bike without one
Good luck and let us know what happens because it may help someone else
TB