I just did the first service on my and a friends 400ex. When we got them back together his was blowing tons of blue smoke. When I adjusted the valves, I did it exactly yhe same as mine so I don't think it is that. I did notice he used alot of oil on his air filter.

 

yeah, it is sucking oil from the filter..it will look like a forest fire. Take the filter off and squeeze the extra off