2005-2009 Honda TRX400EX/TRX400X Service Manual, Page 55Get this manual
MAINTENANCE AT CRANKCASE OIL CHECK BOLT
The crankcase oil check bolt is useful when checking the lubricationth oi pump adjusts the oil level so that the crankcase is always kept at the proper levelIf this check shows othe rwi se, some portion of the lubrication system is not working properly Do not check the oil level immediately afte the engine has been operated at high speedsMake sure that vehicle is on firm level ground wh ile idlingAll ow the engine to idle for few minutes to stabilize the oil levels Th crankcase oil level is correct if the il is lu sh wi th the bottom of the check bolt hole
OIL CHANGE
Change the eng in oi with the engine warm to assure comp lete and rapid draining Start th eng ine and let it idle for few minutesStop the engineRemove the oil filler capdipstick from the oil tank