Right, tonight I tried again.
Even when I use the battery from my road bike, the DD bike won't start (actually the road bike won't start neither but at least the battery is strong enough to make the engine reving...).
So when I use that battery on the race bike, same thing: I can hear the sound of the stuff which should start the engine but only for half a rev or something like this... then nothing happens. And if I push the red button again then still nothing happens. I must then put the main switch (which replaces the key) in "OFF" position and then back "ON" to try and get my half rev...
PUTAIN DE SALOPERIE DE BECANE DE MERDE QUI FAIT CHIER SA RACE!!!!!!!!!!
ok I feel better. But I still don't know what to do. I forgot to mention that to save some weight I got rid of most of the wirings which I thought were useless. So actually I've removed (ahem... cut) everything going to and coming from the dashboard.
Any idea?