GT sounds like you should look at your clutch to start.

Evader, it should fine? Do you have it set right? as per the manual? I have my friends and it idles ok but now the piston and sleeve are shot ofter 5-6 runs. Is it new? set it to manual settings and then take off air filter(be careful they are fragile and tear) look down into the carb and make sure it is open enough. 1.5 mm should be good. Also make sure your glow plug is really glowing bright red. See if that helps.