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!

Lean on the idle, pilot ckts, rich on needle and wot ckts. If you put on a less restrictive air kit, then you need to rejet. when more air is coming in, it's across all carb ckts. the stock needle is too fat at the area's of the needle for the idle, pilot ckts, so it's lean in the low end ckts. main jet will provide some gas in the over lap of ckts, but the stock main jet is still too big, then you have the high alt. to deal with. The taper and the straight portion diameter of after market needles are different than stock needle. They allow more gas on the low end ckts to balance the additional air flow from a less restrictive filter.

Hay GJ,

The reason you see smaller numbers (mikuni jets) when people talk about jetting here is this: Aftermarket needles are tapered differently than the stock needle. They get thinner more quickly from bottom to top, making them "richer." This makes a smaller Main Jet necessary.

It all balances out in the end.

Mid Star summed it up pretty well. The stock needle is really fat, its designed to run the bike largely on the needle by being over restrictive and not let much fuel through. I think this was so they could get their EPA numbers where they needed them to be. The large jets are to help make up for the fat needle, and they are really too big but the needle compensates. Aftermarket needles won't need that big main jet at all. Even at WOT.

At WOT, the stock needle is still governing the flow quite a bit. The Aftermarket needles pretty much get out of the way by then and let the main run pretty openly.

Gram

GJ, ola!

You have two problems working against your bike right now. One is of course the elevation we're at. The second is that you've opened up your bikes ability to breath in and out easier. Both conditions cause a stock carb with factory jetting to run our bikes way richer than they were stock.

I copied Rk's settings and found them to be pretty much right on for our area. It's a really good starting point that you can refine to your own liking or just stick with if it fits. Personally, I am using the Dyna jet kit. Barons is just as good I'm sure.

I recommend you get replacement hex head screws for the bottom of your carb bowl before you get started. The original screws are soft metal phillips heads that strip easily and can be tough to get out the first time, let alone reuse. Ace hardware carries them in stock around here. I also recommend replacing the phillips head screw that is used to tighten the air intake to the carb with a hex head. Just because it's easier to get on and off for adjustments during testing.

While you have it all apart anyway, you might consider porting your manifold while you're in there and checking your float level.

Ratl.

GJCARVING if you want to educate yourself about your carb and jetting go to my site and download the Mikuni manual and the SVS cure which has a bunch of jetting info in it. Besides we are always here to help you.

GJ Definately check out Curts information without his information and the terrific assistance I have gotten from Erbman, Curt and the clinic as a whole would never have been able to do the work I have done thus far. You are certainly in the right place for a ton of really good and savy people who are more than willing to assist you.