w up welcome new myself here. to tell you the truth if you setup you bike right you'll never have any problems. ive had my shee for almost 2 years and never had any problems with it except once with the clutch because i lent it to some noobs. Other than that nothing, i just recently tore down my engine because i want to setup for racing and the stock cylinders are practically brand new and its an 04, all it needs is new piston rings and it will be like new. It just really depends on how you take care of it. a 400ex dont get me wrong is very realiable too, got a friend that runs the shit out of it and never takes care of it and its still running fine.