Full rebuild??

No piston ring!!

I bought a 96 kx125 knowing that it needed engine work, i bought it thinking it needed a full rebuild. The guy i bought it from said he just ran it too hard one day and it died on him. Today i decided to take a look at the plug and take the head off of the cylinder. The plug looked like the engine had been running a little rich. And when i took the head off the top of the cylinder the piston looked good with the normal carbon build up. I looked in the exhaust port to look at the cylinder and the side of the piston and the piston doesnt have a ring on it. Could the ring have gotten into the bottom end or would it go out the exhaust? When i kick the engine over is has a decient amount of resistance at BDC. After reaching TDC the piston wobbles on the down stroke. Just wanted to see what you guys think, i dont want to take the cylinder off until i get the repair manual.

yeah but i dont know what to do with the power valve

k, today i pulled the cylinder off and it looks like i need to rebuild the bottom end too, there was up and down freeplay in the large rod bearing, i ordered a repair manual and plan on buying one of eric gorrs books or videos, luckily i have access to alot of the right parts that you need for bottom end rebuilds at my dads work such as hydraulic press, impact wrench, digital caliper, even micrometers. The only thing that im am not to sure about it honeing the cylinder i have heard not to hone KX's cylinders cause there plating is thin, i guess i will just call eric gorr and see what he says.