First off I got a new 300ex for Christmas and couldn't be happier! I was looking through the owners manual and it said the 300ex is jetted lean for emissions or something. Well in the winter its probably not a problem but once summer comes I dont want it running any hotter than it has to be. So do you guys think I should rejet it, and if so what size jets? Thanks for your help

 

actually the problem will be worse in the winter, as the air is cooler and contains more oxygen. As for what jet sizes to choose, Im not familiar with the 300ex so I couldn't be of much help there. Probably 1 or 2 sizes up and fine tune from there.

 

Actually, since air is denser when it's cold, running lean would be more of a problem in the winter then in the summer.

 

whoa, sorry dill, your post wasn't there when I replied.

 

The stock main jet size is a #122. I wouldn't touch it if it's a stock machine. It's setup for that and it runs awesome the way it does. Once you add on a pipe then there is a need for a rejet. But stock, I would leave it be.