I have my own consulting company in Europe. Can I be on a b1 visa and work with and get new clients in the USA and bill them from my home country? I will be in the USA for about 4 months per year.
B1 visas are complicated, ill defined animals but this is not allowed. In the normal course of events, this is clearly not allowed but there's a "B1 in lieu of H-1" (or H-3) scheme where it might be. But, in 9 FAM 402.2-5(F) (U) Aliens Normally Classifiable H1 or H3
In order for an employer to be considered a 'foreign firm' the entity must have an office abroad and its payroll must be disbursed abroad
You do not have an office abroad, do you?
the source of the employee’s salary must be abroad;
Which I believe is not the case.
Finally, consulting a lawyer is advised.