Working on neighbors 2001 Yamaha Bear Tracker 250 carb. Mikuni, and have a question about the jet located under the carb., just OUTSIDE the bowl cover, directly under the engine side "carb to engine connector." Question is; do I bottom it or do I back off snug bottom any turns?

Carb. was dirty but not that bad. Neighbor said ATV would backfire when he tried to start it, and once it backfired....try no more, it would not start! Getting good gas flow fm tank, air cleaner is like new. When it did run last week or a bit more, it idled fine...don't think it is out of time!

Someone give me an answer of that jet question so I can put it back on the machine and give it a try.