This video is a how to assemble a 125, pretty much the same as the 50cc,
This is what's involved to assemble it, except you wont need to fit the crank etc
Yeah that's a bit too much for me I think. Gearbox is were I usually draw the line. Anything else I always give a crack.
Might just get someone to do it.
The reason I'm going 4 speed is man China motors have come a long way. A 125 china beats this thing and it's not slow by any means. That extra gear would make all the difference though.
It you went back to stock you would be able to get a head , cylinder & easily enough , there would be some laying around for sure
Theat way you wouldn't have to spend anymore cash as it's got everything , and stock class is a lot of fun