I got an 80cc 2-cycle engine off of ebay. I have gone through 3 CDI'S in the past few weeks. Everytime it works for a little while (about 5 minutes) and then shuts off, never to work again, until I replace the CDI. The first 2 were new and the last one had been on another motor for about a year. Why would my motor kill it after 5 minutes when it worked so well on the other one? Where is the best site to order a replacement? I want a motor on my bike so bad but am about ready to call it quits...any ideas?