I recently bought a 2003 Honda Elite 50 engine to swap for performance on my 87 NB50 engine. It is an AF16 engine. I have tried to upgrade the cylinder with 72cc kits, but they keep blowing with less than 200 miles. I am running 40:1 premix, but the same thing keeps happening, and one day it just won't start. I am using the upgraded carb jet that comes with the malossi kit, but the same thing keeps happening. I have gone through 3 so far. Am I doing something wrong? What else can I check for? Cylinder temps are unknown, but is that important?

HELP!!!

Stever