that was the same problem i was having with it. it would run like a champ one day, and the next day it would be 3* hotter outside and it would bog. i still have the carb. im going to try and get it to work on my wifes bike, but if it gives any problems it going on ebay and ill get her a 34mm PJ. that carb took me about 20 min to tune and it runs like a champ.