Right ok, bought the lexmoto xtr s 125 off a friend recently, took it out for the first time today and noticed a few things. 1. I'm not sure if it's normal or whatever but the bike feels as though the back tyre is loose there's movement but could this be down to the fact I had a 97Honda cg before and it's just different suspension? 2nd of all when I'm on a straight and it's at top speed it all of a sudden starts slowing down, starts jerking but then all of a sudden starts accelerating when I leave it roll or if I pull over for two seconds, at first thought it had run out if fuel.

Any help would be much appreciated