If you have the tools to do it, then go for it. You can get a short block from any Echo supplier. I use the CS-510 but the new CS-520 is what is being used now. The 510 was just under 50cc and the 520 is just over 50cc. CARB rules in California caused Echo to do this. I have paid $169.00 for the short block. I use a WT-201 carb but anything that size would work. I also use CH ignitions with the Bosch cap.