OK, did the dynojet stage 2 128 main jet deal properly with stock exhaust and now the bike stalls.
1. When pulling hard in top gear, above 7000 or 8000 rpm, sputters a little bit like it's starving. Not a lot, just a little bit, almost like it's.. well, starving.
2. Going along and pull in clutch, bike stalls every time, unless I give it a throttle blip to keep it alive or downshift and release clutch to keep the revs up. At idle, it's fine and never stalls. Does it sound like too rich/ too lean or spark plug too cold, float?

 

Might be rich. Especially if you're still with the stock exhaust. You may want to try backing off to 124, or even 120?

Mine was acting similar with the 128 main at 3000'. It's better with a 124 now.

Where did you put the clip on the needle. Moved mine from 3rd to 2nd down (leaner) and that helped too.

 

I figured it might be a little rich. Needle is 3rd clip right now and mixture screw is 3 turns out. My elevation is only about 900 ft.

 

Ya, I'd say rich condition. I have a 2007 I'm running the KLX300 DynoJet Stage 2 with the lid off, a Uni-Filter, PowerBomb Header,Two Bro's Slip-on. I'm at Sea-level to 1600ft
I have the 128 jet and clip third position down, Fuel screw out 2.5. Stock Pilot jet, pops a bit on deceleration but not bad.

My bike only pulls to about 8200rpm about all you'll get with stock cams. Makes good power from 6800-7800.

 

I did the DJ on my 09 KLX250SF as a stage one. I was getting bad mileage and my exhaust smelled like it was spewing money out (Gas is $4+ right now)
I adjusted the A/F screw to two turns as it was from factory but it was still too rich.
I pulled the snorkel out and it started running GREAT but was freeking loud. so I adjusted the needle to the 2nd position and put the snorkel back in.
Runs Great now!

From what I have read and experienced with my bike I would Probably run this w/o a snorkel:
Main 120 maybe even 116
AF Screw 2.25-2.5 turn
Needle position 3 clips from the top. (Possibly even 2 as it specifies 3 regardless of your exhaust so 3 sounds rich to me with stock exhaust)

I have used DynoJet kits in the past on other bikes and they tend to recommend a VERY sometimes crazy rich jetting to start with. I think this has to do with liability on their part.

The best way to find out w/o getting it dynoed is to pull the plug and see how it looks. If there is a carbon buildup on it its probably too rich.

 

I think I'll start off by going to a 120 main and 2.5 turns on the mixture and see how she runs. Thanks guys. As always, help is only minutes away. It's reassuring to hear suggestions in the same direction I was going to take by leaning it a little, considering it ran ok stock once my marine battery could get it started.

 

The power might peak out around 7000 but my stock and now rejetted 2009 has no problem running up to redline. If you can't get to redline then you've got problems somewhere.

It would help if everyone would say which DJ kit you're using. Saying stage one or two is pretty meaningless when the old KLX300 kits are all considered stage 2 and have a totally different needle shape than the newer 2009+ kits which can be set up as stage one or two.

To me, the OP's situation sounds hugely rich on the main. With stock exhaust I just can't see needing a main even close to the 128.

I have heard and found that with our modern fuels, reading the spark plug color is no longer a way to determine proper jetting. It will always read lean according to the old charts.

 

My bike runs past 8000 no problem, just not where it makes good power.
If you look at any of the dyno runs with these bikes it's common.

 

She runs like a champ now. I was about to do the jetting over again, and I noticed that the vent tube on the carb had melted against the exhaust pipe and closed off almost completely. The vent was melted down to a pin-hole in size. As soon as I cut the vent line open, it ran fine. (Also, it's the 124 main that I used, not the 128 as I originally thought. That's what DJ 2152 called for.)