So the other day I did my first oil change on my bike and I over filled it just a bit, after riding for about twenty miles I noticed that my speed in 6th gear when crusing around at at 6000rpm seemed about 5 mph slower. After looking at it for the rest of the ride I am certain that I lost some type of power. I just recently lower the oil back down between the two oil marks. I was just wondering if the oil being filled a bit above the limit could cause such a dramatic drop in speed. I know like 5 mph doesnt sound like much but for a bike that doesnt wanna go above 90mph, 5 is very noticeable and quite substantial.