Really, if you could be held financially responsible for your recommendations, would you tell people to go and build one of these? Like broadcast? (everyone)
Heck no. I won't sell the kits to rookies either.
I do however recommend anyone in my area looking for a motorized bike have ME build them a good one ;-}
Seriously though, the kits don't just snap on like a Lego kit because the bike is not in the motor kit, and there are a LOT of different bike models.
Grubee gave making a 'motorizing friendly' bike a pretty good try with the $300 GT1.
That was like my 3rd build well over a year and many builds ago, but if memory serves...
The motor dropped on the frame aligned perfect for the stock mounts.
Both wheels were
double wall rims, and the back wheel had the sprocket and a drum brake already on it.
The back wheel also had horizontal axle adjusters for tensioning the chain so no bolt on tensioner was needed.
And the bike itself was really pretty nice...
Solid frame, front shocks, tripod kickstand, nice saddle and 3 brakes.
It had some flaws though, namely the handlebar controls...
It had a fixed length dual pull lever for V brakes on the right, and another lever for the drum brake on the left (or some such mess that needed re-doing), so putting the throttle and clutch lever on wasn't fun.
Sadly they didn't pay attention to how the kit muffler would fit and clear the cranks and the tripod kick stand arms were just cheap aluminum and crumpled the first time I tried to get on and pedal start it in place.
Anyway...
No, these are NOT kits with ALL of the pieces required to make a motorized bicycle and therefore will never go together like one.
They ARE however one heck of a cheap way to get most everything you need designed
specifically for adding an entirely new gas powered drive train and control system to a bicycle.
How you fit that bicycle 'last piece' you provide of the kit puzzle is the logic and skill part to me.