Okay here's an update (to show some respect of many of you that help me during this thread
) :
Problem have been solved!
-Changed oil to a lighter one (10w40)
-Install my new clutch cable
-cleaned and greased my clutch release system and pushrod
-adjusted the clutch release mechanism
And the big winner is ...
My shifter linkage was too low.. hence i was shifting partially and sometimes i needed to kick it to get the first gear to engage
Best Wishes,
Laurent