I just bought a 2009 Sportster, and I am finding that the throttle is very sensitive to touch, if I go over a bump the throttle rolls on to easy. I have tried the throttle friction screw but that just holds it and doesn't let the throttle roll off. Any suggestions ?
Try your throttle friction screw again, there's a sweet spot where bumps don't jar your throttle hand but it'll still release when you let go. I had the same problem when I changed my stock grips to something fatter.
You're having trouble because of your arm position and stiff grip. Relax your grip. Lower your arms. Install a rubber Kury throttle boss. Adjust your bars.