Re: centrifugal clutch
I had a centrifugal clutch on a Rupp mini bike when I was a kid about 40 years ago- it worked well, and I still used it when I took off the Briggs and put on a Mac 50 cart motor.
I'd like to get one now, especially if it could still pedal start
I looked at the ad for one advertised on ebay with a pull start, and the assembly then sticks out the side of the motor an inch or more, and obviously would not then fit between standard bicycle cranks.
Wider ones are available, if you want the expense and the more drastic deviation- search under "bicycle cranks" on ebay
Back then you could get the Cent clutch in different size and teeth number for the minis.