I think Chinese stuff is perfectly acceptable in quality as long as you pick and chose major name brands and use them appropriately.
Taking a $89 bike and motorizing it contains inherent risks. Metal fatigue at weld joints on cruisers is a biggie, because they are designed for style and not necessarily for strength, like a road bike or MTB.
Everything you do is at your own risk, and I think you would be astounded to find out how many of the products you use every day come from China. Japan has gotten hit so hard, China has really put a lot of effort into making stuff worth buying. My Razor dirt bike is tougher and faster than a real CRF50 and it contains almost all Chinese parts except for the intake scoop that's off a Mercedes, lol.
My opinions on Chinese products have changed completely, you just need to know what you're getting, and not expect the world from items that you were able to get at 50% or less than from Europe, Japan, or North America. Their spec sheets for electronics are horrible at best.
In reality, for bikes and scooters and stuff, you don't need GP bike technology, and there are plenty of CHinese frames that have the engineered SHAPE that is proper for optimal strength and fatigue resistance (flex minimized).
Just use your head, inspect welds, try to find evidence to tube thickness at brake line cutouts, and you will be fine as long as you're not dirt jumping under motive power with flat landings. Overbuild it and make more engine power to compensate, its the safe route.