When we was ridin i sometimes let my thumb rest up on the steel throttle casing. And when i ride under the power lines it doesd somthin to the electronic throttle that causes the electricity to bite me if i am touching the throttle casing.
Scotr
The Steel throttle casing needs to have a mechanical ground to the frame (the bikes ground). It seems like it would be done that way when it it attached though, so check that it's attaching hardware is tight and correctly attached.
The magnetic flux created in close proximity to the high tension lines can generate electrical energy in any circuit and if the throttle cable is an open circuit to ground it may be arching through or using your finger as a path to a complete circuit. Insuring it is grounded at the bars where it is attached should be the cure.
Bring a small coil of wire under those power lines with an AC volt meter attached at both ends and see how much voltage is generated. The higher the voltage in the transmission lines, the closer the proximity, and the longer the wire in the coil the higher the voltage that it will make.
I once asked a rancher why he had four strings of barbed wire on one of his fence lines and only 3 on the others he said that gives me a complete circuit under the power lines!