Well, I've had a lot of good luck with these Harbor Freight motors. They're pretty solid. I have one that is fairly modified, and another that is pretty stock. Both are solid. Your kids will learn how to roll the throttle pretty quickly. My stock motor is on a mini, but my modded motor is on a kart. I haven't been brave enough to stick it on a mini yet. If the stock 212 will toss me, the modded bike will require a wheelie bar. Look into a flywheel and billet rod, and then pull that gov out. You'll white knuckle that thing the whole time, I'm sure. I've got a 5hp briggs that runs on alky that came with a kart I have. I'm still planning on sticking it in a small four wheeler frame. I think that will be a lot of fun for the kids (who'm I kidding, it'll be fun for everyone). That motor won't see the woods. It'll be for the neighborhood
only!