starts up and runs but will not rev up past 4000 rpm starts bogging cleaned out carbs tank and fuel line and still runs the same,i can let it sit and run for alittle bit then it will die and really hard to start back up ,bike was running fine untill took on a long trip then it just started doing this any help would be very helpful , think its not getting enough fuel open it all the way up would only rev up to 4000 held it open and dumped gas in carbs and it reved all the way a few times untill fuel was burned up