should i adjust the a/f mix above 4000 feet?

[bdrue]

i have a 2004ex completely stock with 42 pilot and 150 main, a uni air filter and a sparks advance key.

[cals400ex]

at 4000 feet, you won't need the 150 main unless it is really really cold given that your only mods are the key and the filter. also, at that altitude, a 42 pilot jet might be too much. what you can do is get your bike to full temperature. then let the bike sit and idle for a minute or so without giving it any gas. shut it off and check the plug. see what color it is. this will tell you if your rich/lean on the pilot jet/fuel skrew. you may already know this, but the fuel skrew and the pilot do the same basic thing or work together. the fuel skrew is just a fine adjustment for the pilot jet.