alot of flame outs , eating plugs ,hard to tune , dont like the cheapness of the sirio carb (compared to others ) the funny thing is , I have run the sirio .23, sirio .30, and the two collaris .30 and .32 and they all ran the same for me , like crap , now It is probably my error , but I have other engines that have run perfectly for me , it just seems like the sirio brand , I dont know