Broken rings


My son bought a Suzuki Streetmagic with a 70cc Polini Cylinder kit on.
It was driving fine for a couple of days, but then suddenly it would not go to high rpm's without going out.
The sparkplug was completly black. We exchange it and was runing fine for a while, but then the piston rings suddenly broke. The psiton has burned oil on top, not carbon. Is it getting to hot ?? how to get temp down ??

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Staff member
Maybe you have tightened the cilinderhead with to much torque.

But it's maybe better explainable if you could post an image of the piston and cilinder?
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