what jet

[j400exrider]

Does anybody know the stock jet of the 400ex in missouri, and what i should bump up to.. cause i will be getting a pipe and filter pretty soon here.

[eldoexrider01]

well if you are at or below 3000ft. a stock main jet is like a 148. if you go with an aftermarket pipe and filter. a dynojet main jet will be a 146 with lid on 165 wit the lid off. depending on your pipe recomendations. and dynojet jets are measured different. so if u kept your carb brand jets i would go around a 155 main jet with lid on and like a 170 or so wit the lid off. this is around a guess of sizes because it will be different where you live. but its an idea.