2008 Tomos ST W/A55 motor, stock jug/carb. Last night I installed the performance kit from 1977, along with a technigas next pipe. The kit included a Uni air filter, and infuser, main, and idol jets. Along with this I have a 26 tooth front sprocket. On the test run I could tell that I'm gonna need some help getting the carb tuned right. Very slow off the line, and in the low RPM s of 2nd gear. On a nice down hill section, I hit 47mph, (GPS), and suddenly I got a huge back fire. I eased off and everything seemed fine. There doesn't seem to be any damage. Was I getting close to seizing? or am I running too Rich? WTF