Just talked to DynoJet. Told them I needed larger main jets for the kit as my AFR @ WOT was still lean - even with #132 and 4th notch. The quick answer was that the kit was not designed to work with a slip-on (or full aftermarket exhaust) and LID OFF. Sure enough, the instructions are clear that stage 2 is for lid on, snorkel removed!
They do not make a kit for lid off and sent me to talk to their jetting specialist about my needs.. I will post that conversation when it happens...

 

Just got off the phone with the/a DynoJet jetting specialist. In a nut shell, they have no data for jetting our KLX's with aftermarket exhaust and lid off - not to mention adding in the Marcelino Cam Mod. They developed the kit running a stock exhaust with lid on, snorkel in/out and that I surely would need larger main jets than are in the kit.

 

#134 and 136 main jets are on their way.. Testing to ensue..

 

That's some good info. So after talking to them, let me pick your brain..

If that's the case then at 900-2200'ASL, I should just start with the 124, if I'm keeping the lid and (maybe the) snorkel, if I want it to be a bit rich? I think I'm pretty good now(perfectly lean - I get 68mpg flogging it at 7K rpm) with the stock set-up and a 300 exhaust, but I want to change my air filter, and I know I am on the edge with jetting now.
It's fine, but definitely lacking on top, not lean or rich according to WOT back to 7/8 tests, just not enough. So time to uncork it a bit and get a wee bit more power.
I was going to get a pumper, but cash flow isn't enough for that, so I finally decided to get the DJ kit. And now that I have it, I've been dying to get in the carb.
But first I need to find replacements for the carb screws...I've got a bad feeling about getting them out, even with my JIS bits. My bike has seen some weather and if a part(such as my carb) hasn't been wrenched recently, chances are it ain't gonna be easy.

So what jet do you think I should start with?
Set-up is high flow air filter, KLX300 exhaust, no MCM, (no) snorkel and lid on, 250.
Hoping it's right the first time(haha), even though I know I'll be too curious not to try some jets on both sides.

 

Max, DynoJet says that exhaust doesn't matter, run the standard stage 2 with the lid on and no snorkel... That is what they know - That is what they tested - and they tested with stock exhaust.

IMO, you have two choices:

Doing it once and be happy with what you get - Standard Stage 2 (#128/3rd notch, etc) running with lid on or off - no snorkel.

Go big power and know that you have all there is to get,,, then test it up there around 2k ASL. - That is Standard Stage 2 but with #132 main , clip on 4th notch down, no lid.
The bike gains a HP or more at WOT - Fuel mileage should not change from standard stage 2 until your running at or near WOT.

 

Personal experience, I ran air box off, stage 2 kit with 124 and I'm at 21XX' of elevation. Worked absolutely flawless. Added a slip on and a 128 and things really got cookin

 

It's interesting watching you guys do the AF meter thing, but I think you get just as good results by traditional jetting methods of testing driveability, fuel mileage, and performance to fit the conditions...elevation, engine mods, etc. Most people have achieved excellent results in about the same or less time than I'm seeing you guys spend here. Not dissin' your efforts, just an observation.

 

Trust me, I've been doing this for a long time, and I'm good at it, but there is NO substitute for a wideband.

 

Wideband or Dyno Chart and the talent to use the data. Throwing science at the art of carb tuning. I'm finding HP and TRQ that, from my research in here, hasn't been found before.

 

I think your running a TM36, 300 bore, and muzzy exhaust ? Richard Avatar is currently testing a TM on the fly. I am interested in your TM setup/airbox setup due to the great fuel mileage your reporting.