Just got a 50 Jr adventure up and running for my 5 year old. He was a little nervous of it coming off the PW. I put the neighbor kid on it to see how it runs opened up a little as we just got the top end and bottom end put back together. It kept trying to die at half throttle. I took the carb apart and blew some gunk out of the main jet but other than that everything looked ok. Any ideas?