Re: How to Maintain a Motorised Bicycle
1 to 2 minutes seems a bit long. Particularly if you're in Australia (correct?) and it's summer. If you're in the northern hemisphere, and it's winter, then I'd call that time 'not unreasonable'. Though still a bit long.
But assuming it's summer, then that doesn't sound right. But I'm anything but a fuel system expert. I understand the basic operation of a carburetor. But no details.
Could it be that you're running so rich that you're dampening the combustion?
And could a weak spark be so weak that it'll only support mild combustion?
I don't think this'll help much. But maybe it'll percolate some ideas.