Here is my 2004 KX 250 I bought off Craigslist. This is on the trailer after I picked it up in rural Southeastern Oklahoma:
The motor had a slight compression problem as you can see:
The piston was a bit unhappy as well:
My son and I blew the motor apart and rebuilt it with a fresh replate from Millennium Technologies, a Wiseco piston, and all new gaskets:
Since the rebuild, I've added Tusk Wheels and MX 31 tires, 2007 KX suspension redone by Factory Connection, ASV Levers, new side panels rear fender and fork guards, 2014 KXF front fender and number plate, and 2008 KXF Shrouds. I'll be adding DecalMX graphics this weekend.
It's a very fun bike to ride. Love those old two strokes!