Hey seen this in the latest ADB advice with Dr Ross column
Complaint
I’ve recently bought an 08 WR450F and when I go to brake into a corner and pull the clutch lever and then the front brake lever, the brake lever zaps me in the hand! Kim
Reply
Kim, this problem is fairly rare and caused by the front brake light switch on newer WR’s with painted Pro Taper bars not earthing properly. This fix is very simple. Scrape off a little paint where the brake lever perch clamps onto the bars to earth it to the frame
Hope this helps it is worth a try