400 EX starting problems

[Jailor EX]

Can anyone give me some advice, my 400 EX dosen't want to start since I put on my new pipe, I have a KN, 152 main jet, Procircuit T4, Alba rev box. When you crank it over it fires but won't stay running even at full choke. If you rev the crap out of it till it gets totally warmed up it will idle fine. Today I got it started was revving it up for about a minute with a little back fire or sputter then it died. Then it would not fire at all. I took the plug out it was pretty black, I cleaned it up, put the plug back in and it fired right up as long as I kept on the throttle. Then it died again and it won't fire again. I just left it at that and here we are. Oh yah my header gets cherry red too until you can get the B*tch to idle. Please help!!!

[2muchquad]

i would say you have a jetting issue,usually a bike that is hard to start cold is on the lean side.try turning out your fuel screw.you said your pipe gets cherry red hot,make sure you dont have any exhaust leaks as these can cause havoc while trying to track down problems,good luck

[JOEX]

I have heard that some aftermarket CDI boxes cause problems with starting. I'd try the stock CDI to see if it will fix the starting issue.

[xhondakid250x]

If it was black like a oil substance its to rich.

[Dumontexrider]

If your exhaust got cherry red, its a jetting issue, try going a position smaller on the needle
I have heard that aftermarket cdi's make it harder to start in the cold.