i have a 500 that runs good at about 1/4 throttle. more than that its like it runs out of gas then it will go for a second then do it again. i put different carb, fuel pump and fuel shut off from my other 500 on it but it didnt help any. i also put new plug in it. my other 500 runs great with the parts i put on it so i have no clue. any help would be great. thanks jason

 

Check the boot from the engine to carb, spray it with carb cleaner, check the gas tank vent and if not those your cam shaft is probably worn, take the valve cover off and inspect the lobes. yoll be able to see it on one lobe if its worn.

 

is the valve cover on the top or the side

 

thanks kerbbirds for your help. the air box bottom was broke out. i put a new air box on and it runs great now. thanks Jason