I have a 2001 raptor 660 that was doing ok for the first day of riding but on the second day it started to cut back in power at 3/4 to full throttle and sputter and I would get an increasing number of popping from the exhaust. and I also noticed that the snorkel on the lid to the airbox had what seemed like it was drenched in oil. And so I saw that the airbox had a lot of oil on the bottom of it. I lowered the jet size and adjusted the needle clip to make it leaner thinking maybe it was rich but I still got power loss at full throttle and the cutting back didn't really stop. I noticed that it happened sort of slowly like I started getting some popping than I felt it cutting back and sputtering and it just got worse over the day.