I noticed I have oil leak from crank case. from time to time I have to add oil to counter ballance.
oil is not leaking to ground so I suspect its beeing sucked into the crank case and burnt out.
my plug is is nicely brown color so I dont have a major air leak. 0 to 1/3 throttle is not smooth
but 1/2 to WOT is OK and has power. does somebody have a similar experience with this?

 

You will notice the bike smoking quiet a bit more when you are sucking counter balance oil in there,may be time to replace the seals.