Jetting trouble

[atvfreestylekid]

Hi, I'm new to the site. My friend recently bought a 400ex that cuts out alot about half throttle and up. It has a 440 big bore kit, K&N, and an fmf exhaust. Where is a good place to start on the jetting? Thanks for any replies.

-Josh

[JOEX]

Originally posted by atvfreestylekid
Hi, I'm new to the site. My friend recently bought a 400ex that cuts out alot about half throttle and up. It has a 440 big bore kit, K&N, and an fmf exhaust. Where is a good place to start on the jetting? Thanks for any replies.

-Josh
Welcome to the site.

sounds like it's too rich on the main and possible the needle. What's the current jetting?

[atvfreestylekid]

we think stock.

[JOEX]

Originally posted by atvfreestylekid
we think stock.
That's not good:ermm:

Stock is :
148 main
38 pilot
Needle clip in the middle slot

Your friends should be around:
150-165 main (Lid on or off?)
40-45 pilot
Needle clip middle or second from the bottom if it's adjustable.

Numbers are kinda broad because there are many variables to consider. Air temp, altitude, cam....

[atvfreestylekid]

I know it's prolly lean. But this is how he bought it. trying to set things right. He's running with the lid, around 800 feet above sea, and aprox 60-70 degres.

[atvfreestylekid]

bump