"Doing a top end" is so much more than just changing a piston. This is how I do it. It takes me around 5 hours.
https://www.bludlubricants.com/ Use code TT15 for 15% off.
https://www.emperorracing.com/?er-ref=chuck&campaign=YOUTUBE
Oil change results: https://youtube.com/shorts/z4WwUPDs4Q0?si=LhnikErHoF7fvCqD
KTM power valve video: https://youtu.be/Rjs1hCfLzJE?si=E6riX3hV6mj2Tsl9