it will either be fuel flow i.e a blocked fuel filer/faulty fuel tap/broken vaccum pipe/blocked pipe/blocked fuel cap breather/blocked carb jet/ badly adjusted carb float or it may be a spark that is dissapeared, coils often play up on these and they stop working when they get hot
so get it to cut out then check to see if it still has a spark at the plug by undoing the plug and pushing the cap back on and earthing it on the head and then kicking the bike over to see if it sparks
what is the time gap between it stopping and starting again by the way
adam bike doctor, January 2012
