400ex Carb on 350x PROBLEM

[350xx]

Hey guys.
So my 350x has a k&N and a freeflowing exhaust, otherwise its stock.
So i finally got a 400ex carb all rebuilt and put on my 350x.
After 50 kicks it starts.
I turned the pilot to 2.5 turns out and it doesnt really want to idle.
you give it a tiny bit of throttle and when you let off it goes pum pum pum.
when you give it 1/4 throttle, maybe a bit more, and then let off it goes pum pum BANG!!!! BANG!!! lotsa backfiring.
So i turned the pilot out more, to 4 turns, still backfiring but idles a little better.
I put a new plug in before i did this.
Took the plug out and there was no black at all, white.
LEAN right?

But i cant adjust the pilot out anymore..
Any clues guys?
Thanks!

[Twilight]

Need new jets in the carb. What are the jets in your 350x carb? You need to do some trial and error probably.

Also make sure there is no air leaks.

edit; 42 pilot jet and a 165 main should help you

edit2; bad fingers...

[350xx]

Im using the stock jets for the 400ex in the 400ex carb.

[Twilight]

thats not much help, what are they?

[350xx]

The slow jet is 38 and the main is 148

[Twilight]

have you made sure theres no kinks or bends in any of the cables?

[3wheely]

Sounds like way lean to me. Do you have the stock filter to put on and try for now? K&N's allow a lot of air flow and will cause lean conditions. It might be enough to get by until you re-jet. I had to do this to mine.

[350xx]

Im thinking it needs jetted differently. With my 350x carb it ran perfectly.

Cables are all fine.
What do i need to change to get it to run richer?

[3wheely]

On a stock carb and stock bike it's 1-3/4 turns out. Obviously it would be different with a 400ex carb, exhaust and filter.

[3wheely]

Go smaller. It's trial and error. Buy a few to save time.

[350xx]

yeah, i have it at 2.5 turns out, but super lean still..

[350xx]

go smaller what? main jet?
Why does twilight say to go larger on the slow jet?

[3wheely]

I thought the further out the leaner it gets? Have you tried less turns? If still no difference you probably need to re-jet. Have you went to the technical section and read the thread about tuning and jetting? It's pretty helpful.

[Twilight]

the jetting i gave should be the equivalent and will get you on a good start. run it on those settings for a ride, take out the plug and do a plug chop. From there you can either post pics of what it looks like, or you can go from there and find the perfect jetting.

[3wheely]

They both do different things depending on the setup. Read up on that thread. It's very helpful. Jetting is never fun.