In the last week I have done the muffler mod and rejeted my prairie with #145r and #142f jets. I really didn't ride it much with the factory jets, for fear that I might burn it up, but today when I took it out it seemed slower than normal and I couldn't hit as high of speed as I usually can. When I did the muffler mod, I ditched the spark arrester, but left the exit hole the factory size to keep down the noise. After riding I was really frustrated as I really have to work to pull a wheelie now. Maybe I'm wrong, but I think it may be running rich. I pulled a plug and it had a light brown coloration, not as light as tan though. I do have the stock filter yet, so maybe I don't need to rejet. I live in Iowa, which is low elavation. Please respond, for fear I will get beat by a grizzly.

 

With just a muffler mod, you may be rich. Go with an aftermarket filter and a DG snorkle and/or holes in the airbox.