Have a look at this ignition diagram for the TDR250:

The TZR is similar but it has separate CDI powervalve controller and so it needs a common earth for the CDI and for the powervalve controller.
Check all those black ignition earth wires and that it earths to the frame (at the coil) and that the frame is clean bare metal where the coil mounts.
Here is the full tzr wiring diagram:
