i had a 1976 rd 400 that was recently stolen from me and i sure miss that bike i learned a lot of respect for the rds rzs and loved that ol bike but anyway i had experienced the same problem u are talking about and it never made any sense because when u hit kill switch the bike should have no more spark or turning key off should doit even if throttle cable stuck shouldnt have no spark to ignite fuel i never had mine long enough to get into why it did do that anyway just wanted to say enjoy your bike and let u know that it happened to someone else Russ