Hey all i just purchased a KFX 50 for my son and ive had nothing but issues. At first it wouldnt idle unless on choke. So I cleaned the carb and jet, replaced an extreamly black/wet spark plug, and ajusted the idle screw back to stock settings which seemed to fix most of the problem. My son took it for a 45 min ride and it started to loose speed and when he let off the gas it died. I started it again with one pull and it had all its power back and we had not issues again that day. We took it out again today and it had the same problem seven times and the last time it would not start again. I checked and made sure it had blue smoke coming out of the pipe when it was running. The only thing i can think of is a lose of compression, an electrical problem (CDI maybe?), or overheating. This is my first two stroke that mixes itself and the oil is full.