Well, guys, since the other night I put 3 washers between e-clip and spring holder (for which Dynojet said is a correct placement). I cleaned the slide. I wiped the inside of the air filter a little bit, but it wasn't really soaked.
I was hoping the problem would come back, but I've been riding the bike for 2 days now and it is running without any issues. I looked at the spark plug and it is on the lighter side of the tan color, but I figured it is still tan.
So unless I encounter the problem again, the conclusion is that the slide was getting stuck and either 3 washer fixed it or cleaning it fixed it.
Thanks all of you for the advise, I definitely learned a lot.
If the problem comes back I will post some more.
Oh, and GaryC, come on by, Coronas on me!!!

 

Hope you got it licked!!
Try this, from a slow speed in second or third,, nail the throttle wide open and hold it there until you have to shift, but don't shift, close the throttle down and let the engine braking slow you to idle. Then see if you have the same problem.
Mine was OK until engine braking was used, and the butterfly closed in the carb, the vacuum would yank the slide up so hard it would stick.
Good luck and let us know.

 

For a few years, Dynojet had a problem with the needles for the KLX300. They were too large in diameter to fit down into the slide. Dynojet never confessed to the problem but WE knew about it. Remove the slide, take the clip off of the needle and see if the needle will pass all the way through the slide without binding. If it binds, either drill out the slide hole or sand down the needle.

Good luck

Ride on
Brewster

 

If my needle didn't fit right... I'd return that puppy in a heart beat.
Glad it seems to be running right though

 

Oh, I beat the crap out of that throttle yesterday. Redlined it couple of times in 1s, 2nd, 3rd gears and closed it all the way. Mostly to see if it is popping. And it is a little bit but only after hard acceleration and closing throttle all the way. It didn't stick. I will try it over the weekend as well.
And GaryC, now that you mentioned it, that's exactly how it happened first 2 times. I would go wide open, and then come to a stop with the engine... and it would die. So, your Coronas, are nice and cold, in my fridge. Except it is a 4 pack now.

Quick question for the ones with Kouba screw. Mine is out 3 turns and seems like it is really easy to turn at that point. I afraid it might unscrew more and fall out from vibration. Am I paranoid for no reason, or do I have a valid concern?
Thanks

 

Any more than 3 turns out and it starts to loose tension from the spring inside, and that can cause it to be able to vibrate out. If it's that far out you should probably go up one size on your pilot/slow jet.
Now you only have 3 Coronas left
Dan

 

well,, save me one at least........

 

I put close to 80 miles this weekend, including 30 miles of dirt, mud, and water trails. Did not have a problem once.
These could have fixed the problem:
Cleaning slide
Soaking up some oil from the inside of the air filter (wasn't much there to begin with)
Putting 3 instead of two washers between needle and spring holder
BTW. I got a reply from Dynojet regarding washers.
" The washers take up the space between the e-clip and the retainer to keep the needle from bouncing up and down. The stock needle has a thick nonadjustable head. "
Also Kouba screw held just fine and did not vibrate out at all.
Once again, thanks for all your help.