Sure 007, I'd be happy to explain.
It is "best practices" to only change one setting/component at a time. Kevin went a little "off and wrong" changing to 1N and stock spring all at once. While he is reporting good results, we now have to guess which change made the most difference - luckily, Houstons4 also reports and charts better performance with the stock spring reinstall, so it is a well educated guess that the stock spring should stay and tweaks to the clip setting are now in order.. Houstons4 is running a different needle than we are - so his setting of 1N may or may not apply to us..

2N is the calculated setting for achieving proper fueling below 7K rpm@WOT with your bike, Kevins' bike, and any one else running the exact same "mod list" as you..

So, with all the new information that is now available for analysis, I can see that it may be that I/we will need to "recalculate" the proper setup for better fueling below 7K rpm on your bike and others like yours.. Stock spring first, then try 1N, then try 3N, then set to whichever you think made the most acceleration and throttle response from 3K-7k RPM.. If you can't tell any difference between 1N, 2N, or 3N - set it to 1N (for best fuel economy when riding conservatively.)

Now, having said all that, understand that you may HATE the results of the stock spring. I think you will like the results, but the opposite is certainly not out of the question.. So do it first..

 

OK...So I installed a #40 jet (air out 1 3/4 turns) and moved the clip to 2N. I have some bogging at 4,000 rpm. 5,000 is where the power kicks in. I'm will go back in to see if I can get rid of the bogging. The 1N had smooth power deliver, but the 2N will do straight up and down wheelies in 1st and brings the front wheel up about a foot in 2nd. I could only do 1st gear wheelies with the 1N and then it was more controlled. Now I have to watch I don't go over backwards. On the trail I can do third gear wheelies when I have something to bounce the front wheel up, like a slight berm, root etc

 

Wow! Outstanding!
That is "same or better" wheelie performance I got with Lidless + DGR slipon + DJ140/2N(2152 kit) + DJ slide spring + MCM! Check out my wheelie vid on my signature line - I guess your performance is similar/better?

But also important is that your bogging has, once again, returned - it would sure be nice if you could identify exactly what keeps causing it..

After you "re-fix" the bogging, are you going to run 2N a while, or try 3N?

 

Since the bogging is at a lower rpm than before (and not that bad), I'm thinking it may be something to do with fueling and I may play around with the air screw first to see if this helps. I may be totally wrong on my thinking, but no one has come up with a definitive answer to the bogging question, so I'll experiment a bit.

If this doesn't help, I'll go back in. Last time I used some carb cleaner with the pressure straw attachment and sprayed some of the tiny openings. I also wipe down the hard platic part of the membrane with a clean cloth and massage the top part of the membrane into the grove before I resinstall the metal cap. Maybe my fingers weren't clean enough last time.

As far as 3N, I'll probably stick with the 2N. I can't see getting anything more out of the 250 (Plus I just hate getting the rubber airbox hose back on the carb

 

Whoa, what recipe are you running? I presume from a previous post you have not done the MCM?

 

Ok, I certainly understand you "hoping" you can fix it with the fuel screw.. So, lets make sure it's set correctly.

The fuel screw with #40 pilot should be set midway between idle drops.
What is a "drop" ? It's the point at which you can hear the idle speed slow down from where it was.
- with engine warm or hot, idle set at 1300 rpm (or very close to 1300 rpm) with the idle screw.
- Turn fuel screw IN until idle drop - this will be the "lean drop" ..
- Now, while counting the turns, turn the screw OUT until you hear the "rich idle drop".
- Using the counted turns, turn screw back in to the half way mark between the two drops.

This operation really sux due to the hot exhaust header and engine - but it only has to be done once. "Say hello to my little friend"..

 

Also consider that the performance you have indicates that everything is already working at peak efficiency and that you'll have to go back in and fix the bogging (likely a diaphragm seating issue) when you, once again, tire of it..

 

I too have battled the 4k to 5.5k bog and although I never went back to the original carb once I replaced it with another and fixed the issue, I tend to agree with KLXster that it must somehow be diaphragm or slide related.

 

I just set mine from 2N to 1N. Took the tank off and left the carb on...

 

DRM, if you have an undrilled slide lift hole, you are now running the same setup as Houstons4 - so you should have better performance below 7k..

If your slide lift hole/port has been drilled with the 2206 drill bit, your results will be even more interesting to hear about..

At your elevation, and if your fuel screw seat is undamaged (from over-torquing it closed), you should be at 3-3.5 turns out..