wanting to be careful with break in period I used 40:1 which is where my problems with hesitation and bogging came from after this I added 500ml of straight gas into the tank bringing the mix up to 25:1
Adding straight gasoline does not bring your petrol/oil mix up to 25:1 mix whatsoever...All you did was dilute and DECREASE the amount of oil contained within the gasoline.
25:1 mix ratio would have been 5.2 ounces of oil to 1 gallon of gasoline, instead you say you just added straight gas, to your tank diluting the existing oil even more to almost no oil.
Do you fully understand mix ratio's and how it is done when it comes down to mixing oil with the gasoline in the correct amounts and then shaking the gasoline jug vigorously before pouring the mix into the tank?...From what I am reading your doing it all wrong and I will bet your not even mixing it in a separate container, but actually compounding the error by mixing it in the gas tank itself which you can't even shake to be able to mix the gas and oil properly.
Where did you ever get this idea from???...40:1 is NOT being careful with breakin period, of course you have problems...You have described a not enough oil problem, not a too much oil problem.
I added 500ml of straight gas into the tank bringing the mix up to 25:1
After too much oil there's been problems ever since.
What you have described is not enough oil, not too much oil, especially after adding just straight gasoline to the tank
40:1 is only 3.2 ounces of oil to 1 gallon of gasoline...That is NOT enough oil during breakin period, in fact, it is really not enough oil once it is broken in...Adding straight gas only diluted the oil even more.
Your breakin should have been at
20:1 which is 6.4 ounces of oil per 1 gallon of gas.
This chart below should help you in future to achieve proper mixtures, if your using that French metric system thingy, just convert the measurements from the British Imperial system to the French metric.
After breakin is over on a regular, run of the mill, China Girl motors, you need to run NO LESS an amount of oil than 32:1 which is 4 ounces of oil to 1 gallon of gasoline...You have been starving that motor for oil at 40:1 and even less than that with pouring in just straight gasoline into the tank and may have already caused irreparable damage to the engine due to insufficient oil.
