KLX650C starts only with bridging

Servus with each other, I signed up here in the forum, because I’m starting to despair. I’m going to pick up a little bit further and describe how my problem started: About a year ago it started that my KLX warm no longer starts. Cold, however, still perfectly with Choke. On demand in a KLX group I then set the valves and the problem was fixed for a short time. -> I thought that the valve play is too small and thus a valve in the warm At the end of the season, however, the problem came again, so set valves again. Outlet side was a bit too small but not a big difference. Unfortunately, the expected result stayed out now and it still did not start warm. However, rolling up worked. I got a tip to bridge the motorcycle, see that warm starts perfectly. -> 3 new batteries tried out, however, did not bring any success, meanwhile it starts I charged all batteries before installation. Voltage usually drops to about 10-10,5V when starting. Charging current has the Kawa in the normal range. In addition, I have already changed the ignition coil and spark plug. I have already checked connections between starter and battery. I have already found several forum contributions of this kind, but none of them has led to a successful result with feedback. Would be great if someone could help me.