I helped a guy swap out his rollers today on a chineese sunny scoot. He had 7grams in it and was not geting any top end. we put in 4 because thats what he had and that did noting. so I tryed some of my 5.5 grams and he loved it those little scoots move. then we put and open air filter on it and a bigger jet. down a samll hill he can hit 50 easy. me need to get one it was a blast rideing around on a scoot going 50..........He does need to becarefull the belt was hiting the starter bendex. you can feel it hit a few times.