Originally Posted by old motorbike
I'm using 16:1 oil the first week and it still 4 cycles some of the time, mostly at higher revs. (isn't that too rich?)
That's too much oil.
If it 4 cycles with that mix, it will surely 4 cycle when you go to 24-32:1 mix.
Most of the "instructions" that come with these bicycle motors suggests using 16 or 20:1 because that would be the correct mix with ancient, 30 wt. motor oil.
Too much oil will cause rings to stick (really bad) and excessive carbon build up.