Well I found a really good shop right down the road that can do it for about $600 but I wasn't going to get it rebuilt if I didn't have to but it sounds like I have to lol

 

That's a good deal if you can't do it yourself.
I'm surprised the rings wore out that quickly, either the previous owner did't keep a clean air filter on it or the oil & filter wasn't changed often enough, or both.

 

Well he really had this thing in a rough condition, me and my neighbor are going to rebuild the top are selfs, and it had its head lights off and when I was putten them on I found a few things there is no clutch switch and the clutch diode wires were messed up what should I do bout them

 

I've seen many 400ex's around here smoke like a freight train. The common thing I find out about them is they will all have sit at some point for an extended period of time.

Either way find a book and do some repair work and you've got a good deal.

 

It sounds like you probably should. because if you keep riding it like it is. you could end up costing your self more.