I'm thinking about uping the power on my 400ex and don't want to pour a lot of money into it. Will re-jetting the carb help gain power? what are some of your opinions on settings for you area and ride style. Also is this a do-it-yourself job or not?

Thanks guys
Jera '00 400ex

 

I'm a fellow 400EX'er, 99 model. The jetting probably won't change much on its own if you deviate from the factory jet without doing any other modifications. What did the trick for me was removing the airbox lid, putting a White Brothers "e" series pipe on the end of the exhaust, and jetted it up from a factory 142 to a 162 before it ran rich enough. The power gains were definately noticable throughout the gears.

I know you referred to not spending alot of money, but the pipe will only run about $265 or so, and that's not bad for the performance boost you get, and not compared to the amount of money you COULD spend hopping it up.

Myself, I'm probably going to get the White Brothers 440 kit with the 11:1 compression piston and one of their bigger cams. That should do the trick.

Happy 400EX'ing......

 

Your 400 EX carb is already jetted correctly. You shouldn't change the jetting until you have put your mods on. I put on an E-series and filter and I am also at 160 main, although the needle circuit needs some work. I have tried 155 to 170 and we ended up with a 160 by timing full throttle runs. Good luck, I hope your needle holder screw isn't stripped like mine from the factory.

 

Hey Adams44, Were you happy with the power gains that you mods gave you? How about your pipe? I'm considering an E series pipe. I am plannng mods very similar to yours and would like your imput on them. But what it all boils down to is, Did it gain power like you'd hoped