I’m still having problems with my 400ex smoking and burning oil. I can see oil dripping out of the exhaust ports and have visibly seen the oil accumulate on the piston. I’ve replaced almost everything at this point am not thinking it has to be the valves. The theory I’ve gotten from so.e people is that oil is being sucked down from the head to the cylinder on the downstrokes because my valves aren’t seated right. They did look pretty bad before and them I cleaned all the junk off them and lapped them. So is this possible or maybe my springs are worn out and that is causing the port to open enough for oil to get sucked down?

I would just replace the valves and springs but this thing has already turned into a money pit and don’t want to spend more money on something g not needed.

Anyway I’m interested in what you guys think, thanks.

I’m still having problems with my 400ex smoking and burning oil. I can see oil dripping out of the exhaust ports and have visibly seen the oil accumulate on the piston. I’ve replaced almost everything at this point am not thinking it has to be the valves. The theory I’ve gotten from so.e people is that oil is being sucked down from the head to the cylinder on the downstrokes because my valves aren’t seated right. They did look pretty bad before and them I cleaned all the junk off them and lapped them. So is this possible or maybe my springs are worn out and that is causing the port to open enough for oil to get sucked down?

I would just replace the valves and springs but this thing has already turned into a money pit and don’t want to spend more money on something g not needed.

Anyway I’m interested in what you guys think, thanks.