Small Engine Troubleshooting Problems? Ask a Mechanic Now.
Hi, my name is***** and am happy to assist with the problem you are having.
I can see that the generator was smoking and it would do that if it was overfilled. Overfilling the generator engine with oil should not have affected the generator portion of the machine. If this unit is only 4 months old, I would opt for looking into a warranty claim for it.
Here is some information that will help you get started in that direction. https://www.briggsandstratton.com/na/en_us/support/warranty.html
If this concludes our troubleshooting, please rate my response. If you have any further questions, don't hesitate to ask. My goal is to do my best to help you remedy your small engine problem and continue to keep my high rating as a Technician.