I have a yard blower with a bigger engine than that... I've seen centipedes carrying around bigger engines than that for when they get tired of moving all those legs... I once got a bigger engine than that in a box of cracker jacks... Didn't the really old fashioned washing machines come with larger engines than that???
I actually looked at picking one of these up, they're so cool!! Like the website says, not practical by any stretch, but just about the most fun (and most miserable time) you can have! I was looking at a Grom for a while, just because. There's a guy on YouTube who bolted a Ninja 300 engine into his Grom. Alas, I digress, the Monkey bikes have the fun market cornered, and offer the ability to get plated for road use, unlike the walmart minibikes. If I saw one come on the market for a couple hundred bucks that wouldn't give me any issues getting it plated, I'd snatch it up in a heartbeat! Great link, Culcune!