You’re showing signs of profound hearing loss in the mid and high ranges. You really should get your ears checked. For real. This is outside the complaint you’re making.
What you’re not hearing, are the thousands of 250 -500cc learner bikes. Those yamaha FZ6’s, Honda Transalps, ST1300s, BMW GS’s, K and R series, even the wild high end sportbikes are quite quiet at mild power levels.
My personal bikes? all have stock exhausts. They’re less noisy than my idling Jeep Cherokee, and it too, is dead stock. (though it is a very loud machine at idle) “I” am not the problem.
Depends on the engine. Small 2 strokes usually use premix. Big ones, like on scooters or motorcycles, usually have an oil pump and an oil tank. You add oil every few thousand miles.