This was sort of strange. I replaced my stock carb needle with an NITC adjustable need some months ago, at the beginning of the riding season. I then begin having trouble with fouling the plug, running too rich, this when riding around at low speeds on trails and such. WOT - no sweat, ran great. At the same time I replaced the needle I went up a pilot jet size. So thinking the problem was the pilot jet I dropped it back down to the stock size. I also leaned out the needle by raising the clip to the top groove. No joy, still loaded up at putt putt speeds especially at altitude. So I pulled out the NITC needle and compared it to the stock needle. The stocker is at least 4mm longer than the NITC. What's up with that? Did I get the wrong NITC needle? Its the one for the KLX300. Regardless I think I was running rich at half throttle or less because the needle never did seat far enough down into the main jet and too much gas was getting to the motor when the throttle was barely cracked. At least that's my assessment.

I've put the stock needle back in but I haven't been up high yet or spent much time plunking around so I can't say the problem is fixed, but I suspect it is.

 

FWIW i'm pretty sure the DJ needle is the same length as the stock needle, just more taper.

 

Me too. The N1TC works fine at sea level but have had to drop it all the way down at altitude also. Think it has too much taper and hands off to the main too soon. Running at clip 1 has worked, but I have ordered a stock needle to measure and maybe try with a shim. Stock 35 pilot jets dials in at 1.25 turns on my bike, never had any luck with bigger pilots, though the cold bike did warm up faster. My bud has a klx250r, I might steal his needle to play with also.

 

The first time I put the Dinojet needle in, I didn't get the diaphram on corectly and it ran way too rich. Once I had it right, it worked fine. Stock needle has a thick non adjustable spacer on top. DJ one comes with flat washers to take up the space. If they are not used, the needle can move up and down. I put the needle in with the holder and tried it out of the carb to be sure it was right.

David

 

Oh I'm sure he'll like that!

I ended up doing a version of the KLR650 world 22 cent mod, that is drill out the slide and shim the needle with that washer (I think they use a #4 stainless?). Like I said it seems to be fine. I like the idea of the Dynojet needle with the thinner taper though. Just watch out for those shorty needles!

 

Maybe your public health has a needle exchange program?
Just sayin'

 

haha
I removed the backfire screen in my filter box and noticed an improvement on bottom end and also the bike felt a little stronger through the gears. I already had an annoying pop on decel and that did not dissappear.

I adjusted y DJ needle to the fourth notch from the top instead of the third, and changed to a 38 pilot from the stock and a 138 Kiehn main with 2 turns out on the fuel screw.
I was bogging pretty bad
I changed the needle back to the 3rd notch and I was still bogging.
I changed the needle back to the 4th notch and re-installed the 128 DJ main.
This made a big difference. I had a noticeable increase in bottom end and pull throughthe gears.
The bog was gone and the decel popping was all but gone. The bike starts with no choke when the weather is warm. This was never the case before.
I was a bit worried about my trip to Montana/Idaho because of the large elevation gains so I packed a variety of jets for the trip.
The bike ran like a top up to elevations of 8000 feet, with a very slightly noticeable decrease in power at about 7000, but the bike would still pull in 5th gear at that altitude.
The bike is running a bit rich and my mileage is a bit off from before but I wouldn't change it.

 

I toyed around with the 4th notch on mine as well but it was just a bit to rich while cruising so i went back to the 3rd. One i get an exhaust on mine i'll def be going back to the 4th notch. It made a noticable improvement in the bottom end.

 

You know I had thought low end bogging was a function of the pilot jet, reasoning that it happened at low speed when the throttle was barely cracked and that's where all the books say the pilot jet is working. I'm now of thinking that the main jet causes most of the problem, or more specifically the needle and the main jet. I may be wrong but the reasoning is that having that needle pulled up to far and too early out of the main jet (clip down in one of the lower notches or in my case a short needle) means that too much gas is flowing through the main even when the throttle is shut down, or barely open, and the engine is drowning - bogging. The way to clear it's throat is to yank the throttle all the way open and get more air in there, if the engine doesn't die first. At WOT, however, things work great, the engine screams. That's what I believe was happening in my case. So for now, for me, it's the stock needle, shimmed 1.3mm. The Dynojet needle with the thinner taper though could be the ticket, especially if I ever get around to doing the big bore thing.