As long as the bubbles won't interfere with the engine behaviour, it's OK... If the bubbles keep moving and dissapear into the carb without causing the engine to hickup or burp, it's not a real problem.


How is the full throttle behaviour?

Oh... I nearly forgot: Your engine has a cast iron piston in a lapped cylinder. If you followed the advise, you are now running 10 parts gasoline and 1 part synthetic oil.

Cast Iron pistons benefit from a bit of castor in the fuel... Does not have to be much, lie 2% of the total fuel, or 20% of the total oil should be more than enough to maintain a good piston seal.