A friend of mine just bought one, he didn't get a manual.

What are the basics he needs to know? Oil type, oil amount, filters type or part #, things along those lines.

Any other tips would be appreciated.

 

oil type go to your honda dealer and get a 4stroke oil i get the ones that say honda on it just to be safe lol. oil amount im not sure how much wiht the 400ex maybe a quart just put in some and keep checking the level with the stick on the lid to the oil so you dont put in too much and the next time you will have a better idea of how much to put in. You can run any aftermarket filter that is compatable with your bike it will say it on the box. k&n is a paper filter im not really familiar with them and Uni ( what i have) is a foam filter. if you get a foam make sure u get oil for it to (its the oil that catches dirt not the filter). i clean my filter once a week. and change oil every 2-3 weeks (assuming i ride everyday for about 3 hours) i also have to change my filter more often due to the holes in the airbox lid. well i hope that helps good luck.