2006 Eton Viper 90R 4-Stroke ~HELP~

I have bought a 2006 Eton Viper 90R 4-stroke as a project fourwheeler that didnt get spark. So ive replaced the ignition coil, stater, and cdi box and finally got it running. It wiil start up with no problem and run for about 4-5 seconds and then it just dies abruptly. I will try restarting and it wont start until i reset the key by turning on and off. Ive cleaned entire carb, jets and everything and it didnt help at all. Replace fuel tank and ran on new fuel lines... Im in need of what to do next!!!!! Any ideas or help is much appreciated thanks!!