Well it has been a long time, so I'm going from memory but the problem is that the you can't get the screws to engage in the airbox because it will be held too far apart. The K&N has a much larger lip on it than the stock filter and if you try to leave the o-rings in place there will be a huge gap between the bottom and top of the airbox.

The adjustments were at 2.5f 2.75r with the #50s but idle and low/mid was rich. When I ran #48s at 2.5f 2.75r idle was lean but low/mid was better. This is exactly what 8541Hawk was talking about that the idle circuit is adding fuel off-idle. I put the 50s back in and set the screws at 2.25f 2.5r and trying that now. I also built a better manometer from a 2x4, hose, and 2-stroke oil.

EDIT - Carbs were a touch out of sync. My new gauge works great. Idles smoother with those needles backed in a bit but I still have the occasional pop through the airbox.

Yea, you posted that before. I was talking about the jet needle position in the slides, not the pilot screws.

That's what I will start playing with once I've ran it awhile to check plug colors. It could be that the old plugs have just been in there for ages.

Does the k&n filter disrupt the idle at all? Seems to me if that filter did have a negitive effect it would be in the mid-high range.

I saw the thread your talking about and the guy went thru a bunch of Purolator filters. I PM'd him about which one but never got an answer. I'll try to PM him again.

By the photos of the plugs they look almost new, that is unless you cleaned them before you took the pic in the first post. Even if they are old the bike is still way rich, those plugs are so black they almost look wet.

While you did say the idle was lean with the 48s you never did say why you though this and with as large of mains as you have it is kind of hard to understand but it's all good and the plugs will still be black when you pull them the next time.

It changes the air flow everywhere. The last 2 questions for you would be do you have the rubber blocks that go under the filer installed? If so do you also have the foam sub filters in place. Also what kind of mileage are you getting with that set up?

Other than that it kind of looks like you need to reinvent the wheel for yourself, so have fun and let us know if you do ever get it right.

Ok, a little off-thread at this point, but I'm running rich and the bike is almost bone-stock. I am the only owner on my bike.
I have a '98, bought off the showroom floor that year.
Popped on decel, but I thought it was kinda fun even when it stalled a couple times.
Lucky I'm reflexed to grab a handful of clutch when it feels/sounds like something bad is about to happen. :)
I have 15K miles. The carbs have never been monkeyd with.
I seldom get more than 30 mpg unless I'm riding slow, tight twisties with lots of 3rd-gear corners where I want torque to power out the exit. (Unfortunately the good roads around me have lots of blind hills and corners in a heavy agriculture region. Can you say "oh no, hay truck!"
Here's the deal.
Sometime during the first year I owned her I did a partial bypass on the exhaust baffles by drilling holes around the center exhaust outlet. (I think it's 8 holes per can, about 1/2" each hole, can't go look right now.) Mission accomplished, it didn't sound like a sewing machine any more.
After that I would expect it to be running lean.
I haven't replaced the original air filter yet, but again, I would expect it to be running lean.
I had some trouble with cold weather starting from when the bike was new., so I adjusted the choke out a little after I'd ridden her for a couple of years.
That could have been the beginning of all of it.
I changed the plugs for the first time a couple of years ago around 10K miles.
They were basic black, but I've owned mostly two-strokes in my life. They weren't attrociously dirty or gunky, and nothing came off with a wire brush, so I didn't freak.
Lately I've noticed soot around the exhaust outlets, but I'm embarrassed to say that I'm not sure when it started.
Last summer, I had a short period where she wouldn't run at low rpms without half-choke, so I thought "sitting around a lot with gas in the tank and carbs a lot of the time, hope I don't have to have it taken apart and cleaned."
The only carbs I've ever taken apart myself were on my old Kawasaki S2A in high school, and that didn't go well.
I've tried to always use fuel stabilizer if I think she's going to be sitting for a while.
Somebody on the forum suggested Sea Foam, so I ran a can of that through it over the course of several rides and the problem went away.
OK, this year I've noticed my powerband isn't coming "on the pipe" as low as it has in the past.
Up until lately 3000rpm in 6th gear was an indicated 55mph and I could do a full roll-on from there.
Now she doesn't doesn't want to pull below 3100. Not a big deal, but a PIA in my book.
Ideas?

I would start by changing the 14 yr old air filter....

The blocks are in place and there are good filters in there. The plugs were not cleaned. The 50 pilots run much better then 48s. 48s were lean. I left the mains alone for now. It seems to be running ok for the most part. I haven't done alot of high speed driving to know how cruise is or WOT pulls in a high gear.

...needed my coffee
 

Yeah, I realized that a clogged filter = a lower mixture of air to fuel, not vice-versa, sometime after I logged off last night. Doh!
She's been running really cold all the time as well, and I've been thinking that I needed a thermostat but that could at least partiallly be caused by a rich mixture.
Didn't want to have to pull the tank, tho.
Well, if it's coming off for an air filter, I might as well buy a thermostat at the same time, huh?
"May you die from the bites of a thousand fleas," as the old curse goes. Even Hondas and Toyotas require some minimum amount of maintenance, I guess.
Thanks for giving me a chance to think out loud guys. :)