One kit I found that isn't too bad is a Flaming Horse that I bought by mistake thinking it was a Flying Horse. Most of these two stroke kits seem pretty much the same. I have a suspicion that all the motors may be mass produced at one place in China, then sent to different companies who add the parts and send them out. Half of one, six dozen of the other. Here are some things I learned the hard way.
1 Make sure you have a bike that has wide enough pedals to clear the motor.
2 Make sure muffler is tight. Crappy studs tend to strip out. You can rethread stud holes with a slightly wider dye or tap or whatever they are, and put a damn bolt in like it should be.
3 Tighten head acorn bolts.
4 Make sure the stupid chain tensioner is right and lines up with the sprocket. It is a good idea to use rubber inner tubing in the sliding bolt so it doesn't slip.
5 Use thread lock and make sure all bolts are tight, but don't over tighten muffler stud bolts or or crappy muffler studs will strip out. Use lock tight on muffler studs.
6 The sprocket can be a pain. Put center bolts through center holes in metal tri brackets first. Then put all bolts in and tighten like a car tire.
7 Make sure the throttle thingamajig is all the way seated in the throttle pin. Otherwise, you will start the bike and it will go full bore, and you will have no throttle.
8 Make sure the stupid little bolt thingy on the end of the clutch cable is very tight, otherwise the stupid bolt thingy will slide off and go flying and could be lost forever, and you will have no clutch.
9 Make SURE to mix rich at first, and only ride short distances not going full throttle.