Ok have some news - the leak comes from the crankshaft Position sensor mount ,100% sure
Most probably the O ring is damaged.

Do you know if I can replace only the O ring and where to find one ? Can I apply Silicon there ?

Days of searching, checking and cleaning and at the end its the crankshaft sensor ...

 

so any ideas ? should be easy fix

 

either call your local HD or find a parts catalog and see if there is an O ring there and get the part number... a quick call to your dealer should give you the answer

 

Silicon ONLY works IF dry an NO oil.. go for proper fix

 

http://partsfinder.onlinemicrofiche....b=6&c=0&d=2005 FLHR ROAD KING® (FD) CRANKCASE ASSEMBLY W/ OIL FILTER

then click on engine sensors with switches

crankshaft position sensor part number 32707-01B

call and see if that has an O ring - who knows

 

http://electrical-engine-sensors-w-s.../OEM-32707-01/

 

I done all I can from this end..... call your dealer..

 

Thanks a lot !

 

http://www.jpcycles.com/product/432-487

here is he oring..but you can prolly get it at lowes, home depot, etc.. just take it with you and match it up.... Also, sometimes the sensor can leak through the center part where the plastic meets the metal housing...one more thing, you might try just [carefully] tightening the sensor a little, who know it might stop leaking...