Im not sure why yours does that, I should look at mine to see if it does that. But what I do know, is that you should factor about a 10% flex on the speedometer. For example, I’ve hit 119/120kph on my speedometer but the actual is more like 110kph according to gps. it a a small engine and not finely tuned like racing bikes are. My friend who pays $500/year to get his Triumph tuned to precision. I wouldn’t be concerned about that too much. Hope that helps?