second melted piston in one month

[proelton]

Hi
I own one ec 125. I allways had 2 strokes since when I was 16 and now I am 26 and I know pretty well how to jet the carburetor, read spark plug and so on, including ride it. not that i am better than you im just telling im not a new guy on this subject.

However I am having one problem with my ec 125, which i bought 2 months ago. The bike is very explosive and fast, but since i started to ride it harder, I lost 2 pistons. One melted around the piston crown close to the rings (stronger melting near the exhaust port) and stopped working. No major damages to the sleeve or cylinder. I only changed the piston and it was ready to race.

The second piston, which I run the second ride last weekend (tough riding with lots of high rev as I always ridden my previous YZs 125 and 250), is showing the same symptom of loss of power, no high rev and very poor low end. I almost cant go up normal road hills. Im sure this piston melted too.

What do you think it is?
May it be low quality piston?
may it be that it needs one nikasil treated sleeve to work propperly on high revs? I think it is with chrome sleeve.

The Carburetor is jetted right.

I need suggestions, please!

Thank you!