- Nov 20, 2000
I have a still new-to-me '01 400 sx and I recall there were some simple mods like plugging some tube on the carb and rerouting another (vent?) to the airbox. I have an after market filter and a FMF Powercore IV, changed the gearing to 13/54 on the bike and otherwise it's stock. Any detailed directions would be appreciated. I'm just in luv with this bike btw...