Spend the tiny extra bit for these cheap 2 stroke kits, you'll see much less issues down the road. I suggest
www.bicycle-engines.com, good parts and customer service. Get the cheap kits and you'll spend more in the end to make them reliable. Avoid gasbike and kingsmotorbikes(same company), if any issues you gotta fix yourself and take the hit. Not all kits are the same although they look like they are.