I borrowed a friends 73 900 Kawaski with a Spirit attached one day and took a guy on a 90-100 mile ride.He weighed about 210 and with a little effort you could look down and see the front wheel twisting the forks,the tire skipping on the pavement and variatoins of both.At the end of the ride I felt like I had been working out pretty hard and was sore the next day.
If you don't carry that much weight the reactions will be lessened.I don't know if the cop bike has bigger forks than an older Z-1, if it does that should help with the twisting.
In 2004 I flew to San Jose,Ca, and rode a hack back to Ky. for a friend.Differant story this time. The unit was a FJ1100 Yamaha with a Sidebike Super Comet double sidecar. This featured 13" car tires on the front and sidecar wheels and a 14" on the rear.The front suspension pivots on the s-c frame and is a center hub design. The sidecar wheel steers by about half the amount as the front.This setup makes for a sort of three wheel sports car,very sweet.By the end of the 4600 mile trip I did a 700 mile day with no ill effects.