Hard to start.

[Rickyrebar]

I bought my 2003 400EX last summer. This is my 1st bike so I'm new to everything about it.
Started my mods with a K&N Filter & then a WB Series E slip-on.
After installing the slip-on I noticed a HUGE difference in power! Very pleased!
However, when cold starting it now (after installing slip-on), it seems to run very rough, cutting out almost dying. Have to feather the throttle to keep it running for a few minutes before it can be left alone. Now, once it is warm it runs like a champ and like I said before the power is outstanding!!
Did nothing to the jetting, left it stock.
Do I have a problem with the cold start or is this typical?

[mustang93]

typical, the EX is cold blooded

[gimpbzkt400ex]

switch to a #42 pilot jet... I have the same setup except for the K & N I have a Uni... with the e-series slip on... I had the same trouble with cold starts.... I put a #42 pilot jet in... and now it starts sooooooooooooooooooo much easier....

[cals400ex]

yep, i would put in a 40 or 42 pilot jet. also, if your using stock jetting you might want to put in around a 155 or so mainjet.

[Rickyrebar]

Originally posted by gimpbzkt400ex
switch to a #42 pilot jet... I have the same setup except for the K & N I have a Uni... with the e-series slip on... I had the same trouble with cold starts.... I put a #42 pilot jet in... and now it starts sooooooooooooooooooo much easier....
OK so by changing to a 42 pilot it will solve my starting problems.
Will it change anything else?

[cals400ex]

Originally posted by Rickyrebar
OK so by changing to a 42 pilot it will solve my starting problems.
Will it change anything else?


it should make starting the bike easier. however, even with that pilot in my bike is somewhat tempermental in the cold weather. i can usually get it started without a problem though.

[gimpbzkt400ex]

Originally posted by Rickyrebar
OK so by changing to a 42 pilot it will solve my starting problems.
Will it change anything else?


I noticed a little low - mid power increase...