assembly

Hello, I'm trying to install an engine kit on my Mongoose Excursion 27.5". This bike is 21 speed, and has this assembly on the back of the bike. In order for this engine kit to work, it needs to have one large gear on the pedals, and the shifter on the back wheel needs to go. I was wondering...

I have the standard sprocket assembly for my rear wheel for my 66cc engine kit. Instead of the metal sprocket being the most exterior line of things in the order on the back wheel, one of the rubber things is outside on the other side of the sprocket, and the sprocket is in between two of them...

Hey guys I am new to all these motor bikes and I am planing on buying a kit to start one. I have an eye on a 80cc motor bike kit, and I wanted to know which bike would be best. I am focused on speed een though here in Puerto Rico there are a couple of hills, but I live in a relatively flat area...