okay so i had my Hi bird 250 stw for 3 or 4 years now, its a 2008 model. it was used and it ran good. i recently took off the stock air box off of it because it was letting dust and mud in my carb and replaced it with a kand n spectre racing air intake. i also put a hotter plug in it. it calls for a D7 NGK but i am now running a D6 NGK in her. now when i take long rides or ride her hard she will idle great but after turning her off and back on she will choke out with just the slightest throttle. is it because she is over heated or vapor locking or what??? please help.

 

is that little fan in front working? even though it's too little? when i had my hibird, i installed the "original size" plug and increased the fan size and built my own shroud to funnel the air straight to the finned jug. is it running lean? i mean, if it is hot, i understand, but to add a little fuel on throttle and it cuts out would either mean plugged jets, which i doubt cause it runs good-right?, so it would be sucking too much air or have a vacuum leak? i tend to not think so. it may be running too hot? have you shot it with a temperature gun?