OK, I wont be able to attempt a re jet for awhile due to time, but I guess I'm looking for some professional input so I can better understand. I guess it has to do with altitude also. I have run my bike for a year and a half, and it seems to run pretty well. There is some blackness to the plugs, and some people riding behind me say it smells of gas. I take this as being to Rich. It would also pop occasionally especially up in the mountains coming down hill. It would also smell of gas after shutdown.
The bike was bone stock 04 when I bought it in 08. I added a 2-1 propipe to it, but kept the stock air box. I would get around 40mpg which seems pretty good.
I just put a K&N BAK on it. Took it for a spin, and there was hesitation with the throttle. It then left me stranded till I messed with the idle and choke to limp it the 5 miles home. That was not fun. I figured this would lean it out and then go from there, but the bike is running like DIRT. Lots of hesitation with the throttle.
OK, so this is where my questions or more of inquiries start...

I live at 7000 ft, meaning on the stock jetting I would be pretty rich as I have read all the bikes come with the same jetting from the factory. This boggles me on the 40 mpg avg, seems like it should be lower than what I'm getting.

So from what I read on here hesitation is a sign of being lean, and this is where I'm confused. All jetting I see on here goes down in numbers from stock. I guess making it leaner. Even people at a higher elevation seem to lean the carb from stock, even if they have an air kit. By my reading it seems like I need more fuel and should go higher. Which I have never seen anyone do!!!

So, I guess I'm trying to understand that if my bike technically speaking was running to rich before hand, and then when I put the K & N on, it seemingly has gone to the other extreme. Maybe its something else??? I'm just trying to understand better.

I'm not sinking in to the Carb just yet because of time, but when I do it will be my Virgin experience and it's a little intimidating. I'm technically savy in many facets of my life, but never really did any engine or carb work. Anyway, just trying to get some understanding. Any input would be greatly appreciated!!!

Thank You!