The wheel should spin freely. Lift the wheel off the ground and spin it in each direction. When you turn it backwards, you should be able to feel the motor resistance, which is notchy. When you spin it forwards, it shouldn't be notchy. If it is, the clutch is jammed and needs to be fixed. If it's smooth, but with resistance, then it could be your brakes binding, or the seals and grease in the motor needs a bit of running in. I had my kit installed in a Claud Butler and it was noticeably slower than my ready-made Sunlova bike until I changed the tyres and the back wheel. Don't ask me what was wrong with the wheel - I changed the bearings and swapped the motor and controller with my other bike, but it was still slower. With the new tyres and wheel, they are now the same. The battery did take a few cycles to come up to full power. Normally, I would've been happy with the kit and it's power except that I did a side by side comparison and could see that it was slower, but not as much as you're saying, so there must be something wrong with yours somewhere. However, I did do some mods from the beginning: I reduced the length of the motor wires because they were miles too long and would reduce the power a bit. Also, I beefed up the wires to the switch in the battery box because they appeared to me too thin, which would also lose power. Is your kit the earlier one (like mine) with the thick pedal sensor, or the later one with the handlebar display and thin magnetic pedal sensor? Please do this test of spinning the wheel in both directions and report back.
