20% is fine
When i adjusted my carb on the MT2 the screw by the gas line that controls the amount of fuel was all the way out, screwed it in most of the way and backed it out as needed, with the low speed I turned it really lean, backed it out till it didnt stall when taking off, then turned it a little more rich to make sure i didnt run it too lean.
The high speed screw i am still working with i have it bog down a little at high speeds

But when I stop breaking parts i'll get to that
Tiny