Thank you very much Andy
I have the bike fully serviced before the trip and have the oil pump seal replaced and fixed with hermetic to the oil pump housing, it,s leaking to the gearbox and this problem solved
Yesterday I checked spark plugs, carburettion-air screw, etc, all seems to be ok, next is to check coils, ignition cables and pick-ups. Then check oil pump delivery with graduated vessel and clear tubing
I know the matter of jetting can be problematic here and will try on my own whith larger jets if my pump don,t work
I,m thinking about the possibility of center crankshaft seal leaking from one cilynder to the other? but engine starts perfectly cold-hot and runs ok troughout all regimes
I will take advantage of this post to thank all the people publishing here and the administrators of the site, it,s very useful to newbies on this bikes like me