Not on the Valk, but on my SuperHawk.
Friend of mine and I just finished eating and were pulling out of the parking lot onto a two lane country road. Three young guys were walking near where we were going to pull out and gave me the universal "gun it" sign.
I obliged.
That 998cc V-twin stood up on me so fast that I had already gotten the front tire back on terra firma before I realized what happened. The slap to the back of my helmet for almost launching my passenger off the back helped bring me back to reality pretty quickly, too.
I tried explaining to her that I had no intentions of launching into a wheelie - but I don't think she believed me.
Dang, sometimes I miss that bike...
