I wouldn't say that you have to baby a big bore kit. You just need to make sure that you break it in properly, like any other new cylinder piston setup. I heard that you should use a 40:1 mix with a 70cc kit, and run it at half throttle for 300 miles. You shouldn't have any problems after that. I know a kid that has had a 70cc kit on his puch for like 2 years and never had a problem. You just have to break it in right.