• I bought a 400ex carb for my 350x and advice on jetting it from those of you...

    I bought a 400ex carb for my 350x and advice on jetting it from those of you who have made the swap ?

    10 comments
    • Run a 138 or 140 if it is a stock engine

    • Doesn't the stock carb have a 138?

    • i think i ran a 152 in mine

    • Yeah the stock jet is a 138. Start with a fresh spark plug then run it a little while at full throttle pull the plug and check it. Ideal will be golden brown. If its white/gray go up in jet sizes if it is just dark black go down in jet sizes

    • Mine looks good. So wouldn't a 400 carb with a 148 stock jet drown it so to speak? Everybody seems to see a big difference in performance

    • I ran that set up when the 400 ex was just coming out and can't remember what jets I used but I had far from stock setup. I think a 148 would be too much but I could be wrong so I would stage it up or down with a new plug but would start with a stock 350x 138 jet

    • leave it stock from the 400

    • The accelerator pump on the 400 carb is a better design than the 350x. It's only 3 and a half mm bigger but yes it is a substantial upgrade if its accessible. I personally like a 36-38 mm mikuni flat slide

    • I get what ur sayin but if I run a 400 carb on my 350x with 350x jets I haven't gained anything right? Just put a new plug in a month ago and it looks pretty good. Looks dry and crisp unless sits pms-ing that day and just doesn't start good. Doesn't happen often though.

    • I get it. I'll work my way up and see how it runs