No need for speed
I have 2 identical Black Stallion 66cc motors on 2 differant 26 inch bikes . One tops out at 22 to 25 MPH and the other tops out at maybe 20 or less both start easy and idle great . The clutch isn't slipping . The breaks are not dragging the kit sprockets are the same . The slower bike has not enough miles to be considered broke in . The faster bike has . The slower bike was accidentally run for a while with a very rich oil/gas mix and I thought it might have clogged up the muffler but I haven't checked it yet . Is that a good place to start and will break in increase speed 5 to 7 mph ?