[Nospark]

I suggest you look at the basics. Air, fuel and spark.
From the limited info you've provided, I would focus on air 1st.
Fresh oil is always good but, likely not the reason for any improvement in how the motor runs.
make sure the carb is clean and not restricted with dirt or oil. Then check for leaks at the base of the carb & around the intake. You may fand a bad gasket or cracked intake housing. Air leaks of this type make it impossible to dial the carb in. You can check for leaks at idle by spraying carb cleaner or brake cleaner around the base of carb and intake. If you observe any changes in RPM, and your confident it wasn't from over spray down the throat of the carb, you have a leak that needs to be addressed.