Changing Stock Jetting

[j4rdemotox]

I picked up a 2002 400ex that only had like 10hrs on it. Showroom condition. The first thing I noticed is that the 400ex get hot & am getting some blueing on the headers. I am going to change the main jet to #150 from #148 Stock. Want to see if anyone has any other ideas

the stock exhaust is stainless steel...and sometimes when it gets heated it will begin to change to a blueish tent color...its normal and you shouldnt worry about it...if you want to check the jetting do a spark plug test to c if its correct

[cals400ex]

if it is really cold outside or you live at low elevations, a 150 might not be a bad idea on a stock bike. however, i imagine your lean on your fuel skrew. i would turn it out 2.75 or 3 turns from lightly seated. by the way, the fuel skrew is on the very bottom of the carb. it is a bronze skrew. you adjust it with a flat blade skrewdriver. it is hard to see with the carb on the bike if you don't know where it is located. the blue tint is normal. the stainless steel headers will change color a bit.