2005 EC250 Jetting
 

After many hours and $$ spent I have finally got to this set up, still not 100% but its so much better than its ever been

N3EW #3 (I have tried DDK #3 which has a similar effect)
170
38
A/S 2.25

Very sharp and responsive off the bottom end, pulls hard thru the mid range.

WOT is good from low to mid rpm but once it gets up into the high revs it starts to miss again like its running rich. I am assuming that at WOT both the pilot and main are working together. I am a bit nervous to go any leaner on the main.

I really like the N3EW and DDK, is it worth trying a needle that is longer eg DEK.

wow... im no expert but yep, sounds lean. in my 250 i was playing with the N3EW with a 42/178 and i thought that was too lean. gone with a N3EG but on a 38/180. was runnin a 178 but it kept gettin hot if i ran it hard..
hope you got your bike runnin good now though... rip it up...

At WOT you are ONLY on the main.
Do I read that you are opening the throttle wide open off idle and as it revs it is clean at low to mid RPM and then blubbers as the RPM catches up to your throttle position?

I can't imagine achieving proper jetting with that technique. There must be throttle control such that the throttle position somewhat matches your RPM. Its true that at WOT and low RPM the signal is weak (less airflow) so the main provides less fuel and keeps things somewhere close. But the pilot and needle are there for a reason.

My 03 250 likes to be a little leaner off the bottom than most, I run...
185 main
JD red needle 3rd clip
42 pilot
#7 slide
About 2 turns out on the air screw

IMO the gasgas bikes dont seam to be consistant jetting wise from one bike to the next, I'd like to know the squish on some of the bikes that need to be alot leaner than others I bet its huge.

Another fellow NW EC250 owner here, '03.

I too worked on jetting quite s bit searching for Nirvana.

I tried it all and ended up with :

CCK #2
170
38
#8 slide

Temps 45-90
Elevation 500-3500

I don't think you are too lean. My plug is perfect tan and I have many hours on this jetting with great results.

Mine runs spot on! Absolutely no bog, hesitation or hit. Just smooth crisp delivery throughout. It feels like my EC300 in terms of power delivery.

Without temperature and altitude specs, not much help can be given.

I jet my 05 DE250 (RB Designs carb and head mods) for 110F in Phoenix at 2,000 feet using 168/40. 168 (or 162)/38 in Flagstaff at 8000 feet an 85F. Using whatever needle RB-Designs gave me. :)

I forgot to mention the temps and altitude

Where I ride is sea level and the temps at the moment are between 10'C-16'C
(50-60'F)

I probably explained it wrong, here is a better example...

If I am riding in 3rd or 4th gear at 1/4 throttle then open it up to 1/2 and then WOT (smooth throttle control) the bike runs well until the revs get high and it starts to 'miss'. Its definatley not lean, so I could be hitting the rev limiter?

I am glad to know that at WOT its only the main jet working, that means I could try 168 MJ. Its so surprising that I am at sea level and have to lean it out so much. All of the settings that were recommended for my bike are all too rich. Even the bike shop couldn't jet it properly.

I follow you now.
Yes, I concur that you are still rich on the main.

Just keep an eye on the plug and for any signs of running lean. Pinging, high/hanging idle, boiling or excess temps.

The bike isn't using any tranny oil is it?? Certain its not a main seal weeping? As the revs increase so does the vacuum which can effectively pull more oil through a leaky seal. Maybe measure the oil from the trans and make sure you can get out what you put in.