how to tell if bike is jetted?

[razex]

I bought a used 2003 400ex a month ago and it has a FMF Q slip on exhaust on it, does it need to be re-jetted or can I rejet it? How can I tell if the previous owner did the jetting or not? I dont want to harm the bike and I want it to run at peak performance, thanks in advance

[2004exrider]

The easiest way is to pull the main jet, if it says K148 then he didnt jet it.

Jimmy

[razex]

thanks