My R keeps shocking me

Both my R and my dad's keeping shocking us when we touch the throttle housing, bars, or brake lever. What are the common causes of this? What is the first place to look? We both have the factory kill/light switch. I have a pro design kill switch as well. Both wiring harnesses are in good shape. They haven't been all hacked up. The ground wires are grouded to the frame good. Performance is good, not cutting out or anything like that. Any suggestions would be appreciated.