i was just curious as to whag options there are to getting a lil more outta hum i guess top end or hp outta 400ex. i don't want to do a lot there is boring but im looking a few other ideas before i do that.

back info i have a lil older 400ex 1999. but its very cleans and runs clean. regularly maintained as well so far what is done to it is a white bros E series pipe KN air filter and went from a 15 tooth sprocet to a 13 in the front. that for sure helped i went from having to down shift to second on certain dunes to being able to pull third with easy. im also a very light rider in a chick of course but in about 5.4-5-5 and 118 -120ish thanks shan

 

lower the rear down 1,little jetting to the carb,remove the filter lid,there is a carb spacer on ebay for like 50$ good idea,RACE FUEL or jet it total bigger to run e85,timeing advance tab,rev box. if u want to tear the motor apart a little i have more.

 

Read this you will like it.

Honda TRX400EX "Low Budget" Project ATV

 

a pipe is a big power increase along with jetting it and a high flow intake, removing the airbox lib will also add a lot of power but be careful if you ride in the dunes because you will get sand in your motor which will be all kinds of problem, there are a lot of upgrades for the 400ex that arent too involved