firing problem maybe help

i have a typhoon125xr its been running fine then all of a sudden whenever i start it its run for five seconds then cuts out the time between running well and cutting out I've filled it with oil (the right oil) and added petrol what could the problem be please help I'm a bit worried

junk n gunk .

sounds like its a fueling problem as the scoot has been sitting for a good while its possible the carb bowl dried out with what ever left over fuel it had in it, this has turned into a cruddy junky gunk mess and with the new fuel its dislodged it and its blocking up the main jet and pilot jetting .

remedy is remove carb float bowl and carb, remove the main jet and give it a quick rinse in petrol then use a fine thin strand of copper wire to clean the hole, do the same with the pilot jet, with both jets removed a can of compressed air and blow air down the two jet ports to dislodge and remove any gunk junk thats got dragged into them ( be sure to wear safety specs ) , once done fit the main jet and pilot jets back into ports,

old tooth brush and a small drizzle of fuel into bottom of carb bowl, give it a good ol scrub with the brush, tip away old gunky fuel then rinse with a drizzle of fresh, install the carb bowl back on, refit fuel lines to carb, slide the throttle slide back into carb and button the top cap down again, then give it a few kicks/blasts on starter to reprime carb, should hopefully start up after a 3-6 blasts on starter/kickstart