EC300 dies slowly at idle when warm
 

Well, the headline pretty much sums it up.

Pilot jet is #35, and neither of the setting screws (idle, pilot air) has an effect on idle speed. Of course, the engine dies if the air screw is wound in.

Don't know if it's relevant to the issue, but the bike is equipped with VForce3 reed valve.

Any suggestions?

Yeah. Why do you care? As long as it idles for like 3 seconds it won't stall in normal riding circumstances.

But if you have a N1F-anything needle it will run badly at closed to low throttle and small pilots won't help the wet gas blobs being sucked past the too thin needle.

This entirely!

The N1EF needle has a super short straight section, and is rich as all buggery on both the diameter and 1st taper. Most people try and bump the idle up and go to a smaller pilot (35) to overcome the richness, but you're then left with a more inconsistent idle and an air screw with little effect.

Have a read in the jetting threads.

Well, there is the N1EF needle in, with the clip in 3rd groove. The bike came w/ also N1EG and CHN (brass) needles.

I changed to #40 pilot jet, air screw 1 out. Now the engine has sluggish and sputtery throttle response up until the opening of the PV when the bike really takes off and has a significantly higher power output than w/ #35 jet. On a 4-stroke, sputtering would be a sure sign of a lean mix...

Another issue: There is a significant misalignment between the carb body and air filter box outlet, and I cannot make the flanges go flush - not even close. Actually, yesterday I managed to get the carb out of the airbox and used a good hour to get it back there (what a f****ing ordeal). Any pointers?

Undo the subframe,

Throw away those needles or forever be subservient to shitty running.
Your choice.

I always use a heatgun to lightly soften the airbox boot to aid refitment of the airbox. Also what carb size,elevation and ambient temps have you got?

hey man just posting to say i feel you.
i have similar issues to yours.
0 to 1/8 throttle if i roll on throttle then back off it stalls. seems to be rich.
the alignment to the airbox boot is pretty poor. because im taking the carb on and off so much the fastners are getting worn out and the airbox is getting cut by the gear clamp.

one tip for you though. if you loosen the fastners on both sides of the carb then you can rotate the top towards you undo the cap remove the slide, then you can rotate the carb the other way to get at the bottom screws and bowl. this way you dont have to remove the exhaust and the subframe

anyways good luck. ill be posting a new thread with the details of my own woes

I didn't have the balls to use a heatgun - thought that the risk for fire was too great. One question: Is the rubber joint between the carb and cylinder straight or is there any shape? The problem is that the airbox outlet kinda comes inclined from the frame of the bike, and now the carb is actually in contact w/ the frame. And still not nearly flush w/ the auirbox flange.

Carb size I don't know; I believe it's OEM. Altitude is close to sea level and ambient temps have been 15...20 C (50...70 F).

Just using basic math, #40 pilot gives 30% higher fuel flow than #35. I'll acquire #38 (+18% flow), and continue my efforts.

Okay - I thought that there might be an issue w/ the subframe alignment, as the compatibility is so poor, and the airbox is pretty much solid in its own location. Thanks.

Oem carbs have been both 38 and 36mm. do you have a screw top (as 1)or a cast slim top retained by 2 small screws(as 2)??? if you have the later,there will be a hex shape in the top with either 36 or 38 cast in.
once this is established,many here can give you their recommendation.