This could belong in Off Topic, but I reckon it's more relevant to this forum since a bicycle with a motor would technically be a motorcycle. This is the particular kit I'm looking at: http://www.ebay.com.au/itm/70cc-motorised-bike-motorized-push-bicycle-engine-kit-/140601085980 I have been thinking of getting one of these 2 stroke 70cc kits to put onto my bicycle for doing short trips, (ie dandenong to wantirna distance and less) to save on petrol and wear and tear on my motorcycle. It would be a fun little project sitting the kit up on my bicycle. I also want it as something I can thrash around and not really care about and to learn more mechanical skills on. Parts are very cheap - a whole new engine is only 130 bucks - and I reckon could learn to rebuild it myself. I'd rather a 4 stroke kit so that there'd be more skill transfer to working on proper 4 stroke bikes, plus it'd sound a lot less annoying than the smoker, but they're a fair bit more expensive than the 4 stroke kit. The only thing that concerns me is that being chinese 'quality', the bottom end of the motor might be rather fragile. They don't sell spare parts for this apart from the front cog, so I'd be buying a whole new engine each time the bottom end went. But maybe they're alright? Yeah, yeah, I know - "Why don't you just pedal the damn thing?" But I'm lazy. Thoughts, comments? Bad idea? Good for what I want it for?