first four stroke build - advice needed

[Flight Risk]

All I’d like now is for someone to look over the gear ratio and confirm that 2.5 horsepower with a cvt will be enough power to be practical and fun

I'm just curious Toby, in the UK do they not allow 2-strokes, since you mentioned no Grubees. Are you able to get Predator engines as I think they may be more tunable and reliable than a Lifan (though Lifan in general is very popular).
If your mother loathes motorbikes, I'm surprised that she would like a motor-bicycle any better. Is it a stigma thing or a safety thing? I would think she would rather have you riding something a bit more reliable, with proven brakes, lights, and able to move with traffic. They are even bringing back the Cushman scooters and Whizzers. BTW- whatever happened to legit mopeds?
I think you are on the right track with gearing. You can always change a gear after you have ridden for awhile and you may even be able to add a bit of leg power for steeper hills.

 

[Toby woodman]

I think the consensus is that if I can build it I can ride it, just because she probably doesn't think that someone could build a motorbike

 

[darwin]

How do those sprocket's turn the wheel?

 

[Toby woodman]

the chain coming from the clutch goes to the large sprocket, the hub is mounted on a plate to just in front of or just behind the seat tube. the chain to the back sprocket goes from the small sprocket. its just a jackshaft with both sprockets on the same side, in my new version of the jackshaft the sprocket and big sprocket are on the same side. here is a picture.

 

[Toby woodman]

Here it is on the bike

 

[DAMIEN1307]

bike

YEP, It does look like a bike to me Toby...lol.