I went through two st3250's and followed the on line instruction on break in and went to large fuel lines and still had all kinds of high end trouble. I finally broke down and spent the 350.00 for the 35cc 2.13 Cu. Inch OS engine and it runs very nice in the same plane and fuel system that burned out two st3250??? I love my smaller ST engines but everywhere I go I hear the same horror stories about the 3250.