Quadra engines base engine are Mcullah i believe.If you want a good thread check out the thread (dont forget echo),i wish i new how to post a link in here from another thread.hopefully someone will tell me how.In this thread ,Keith from BME(wich uses echo parts as there base engine) tells what they did to hop up there 24cc echo.its probably a 26,just a quess.if you know how to find the displacment of a cyl you can find the exact ccs.if you need the equation i can give it to ya.