I have 5K miles on my 06 Fs650 (conversion) with just a cam chain. 153hrs.
I took an 05 Fe650 to 180hrs with cam chain and cam follower replaced. Except 3rd gear going at 117hrs.
That was a fluke I believe.
And a third 650 I owned was 05 Fe.
Camchain around 120hrs. Still running strong at 210 hrs or so. Sold it.
If you take of it you will not likely have to open it up till after 200+ hrs.
Others here have a lot better stories than me.
Some have sorry stories
Stock Hp as much as 63 I think.
pollo