pto 121, center 115, mag 110, I took the heads off and the mag side piston top is starting to burn off the edge almost showing the top of the ring, I am going to put in new pistons and rings this summer, without taking the cylinders off I brought each piston to TDC and I was able to slide a 14 thousands feeler guage between piston and cylinder wall on each of them, It's probably due for new parts anyway cause there is over 7000 miles on motor without a rebuild, about 3000 of the miles are from racing only.