I have always been concerned about using a bung in the small pipe of an ATV. The bung itself wouldn't be an issue, but once you thread the wide band senor into it it will protrude inside the small pipe. On a car with a 2" or more pipe the size of the sensor does really obstruct the exhaust flow. But I feel on a small ATV/MC pipe it will black at least 20-30% of the inner diameter and therefore reduce exhaust flow.
Then you will be tuning the ATV with a reduced airflow and after you remove the sensor your flow will change and you tune will also.
A suggestion is to use the Exhaust pipe sensor adapters, while they will also reduce flow it is minimal because it will be at the typical 2" opening of the performance exhaust.
I use an Innovate LM-1 Wide band system and the Innovate Venturi Exhaust clamp, see photo. Your existing Wide Band sensor will thread right into it. Simple, no welding, drilling etc and less exhaust restriction during tuning.