Finally solved it. The problem was the starter clutch. Moved to an All Balls clutch.
The funny thing is that the stealer wanted me to pay 600€ for a new stock starter plus installation (that makes approximately 850€) and I solved the problem myself for 57€ + primary oil.
Thanks for the replys.
2003 FLHR, Kerker turn down slip-ons, S&S 510G Gear Drive Camshaft, S&S Stealth Air Filter, Mikuni HSR-42 Easy Kit, Jagg oil cooler.