The fuel mixture is not 40:1 its 20:1. I know it sounds weird but that's what it is.It could be either a 43cc or 49cc. A easy way I have found to measure the bore to see which it is. Is to take a a wire tie and cut the end off that has that small bend on it. and measure 40mm and 44mm and make them on the tie. than slip it through the exhaust port and in the center of it and see which mark it measures at. It's crude but it works.
Well you can wire in a toggle switch. I'm really no good with the electrical crap so helping with wireing a toggle or bypassing the key switch as far as which wire you would connect together I don't know. But if you just want to use the pull start without the key and maybe fix the key or add a toggle later. You could follow the small wires from the coil to it's connector and mark them so you know where they plug together later. than unplug it. Than follow the wire from the starter button mark it and unplug it than plug it to the connector from the coil. Now this will make you starter button your killswitch.
You want to put the choke up to start and down to ride after it warms up alittle.
I would clean out the tank and put a freash mix at 40:1 before even trying to start it.