smells like petrol....burning petrol, very strong. only when im on the go and when i first start it up no change in power (that i noticed) and still sounds the same very thick and very black pretty sure its coming from my exhaust. But i will have to wait til my brother comes over to double check that (hard to see when im the one riding it) cant really say much more at this moment. Thats all i have for now, too dark to see anything outside. Full service just three months ago!