So my Yamaha xcity 125 2007 makes a really nasty rattling sound when I´m at top speed in not sure what it is but it is coming from under the crack case in changed my rollers recently to see if that was the problem but it wasn´t but it made it go faster it sounds like metal when it´s rattling but dose not make it at lower speeds only when it maxing out and it will also limp at max speed as well which I´m not sure why it dose that