Magellan

Hello everyone. I'm new here and I have a problem with my son's bike. It's a TDR 125 1993 and starts fine and runs ok until the bike is actually moved forward. Now I have checked the sidestand switch with a multimeter and all is well. I have even bypassed it too. We have also changed the 2 relays under the seat as I believe they are too related to this switch, but the problem is still there. Has anyone else encountered this or could anyone shed any light on the problem for me ? Any help would be greatly appreciated. Many thanks, Gary.