they DO NOT use Honda/Yamaha engines. I Worked in Honda stealership for a while, and had a few customers come in with these piles of crap. The only way to repair and get parts for these things is to buy two - one to ride, and one to strip parts off of. They look like they use jap engines, but it is a rumor, no truth to it. the mechanics at the shop I was at once ordered 15 different honda kickstart gears to try to fix one chinese scooter, none of them would fit and the customer swore up and down it was a Honda engine. it wasn't.
In all honesty: you buy cheap, you get cheap. If you own a custom motorcycle shop I would think you or your in-house tech would know basic troubleshooting and engine diagnostics. All engines and ignition systems work on the same principles, regardless of where it was manufactured.
Start simple. You already know there is no spark. Work backwards, check the plug cap, wire, ignition coil for continuity and resistance. Randomly replacing parts is not a solution - you might install a bad CDI box and then you're really scratching your head.
compression needs to be at least 100 psi for any engine to run, it may fire on less but it wont have any power. Ideally it should be around 150. If it's a two-stroke, do a leak down test, that will give the condition of the rings and crankcase seals. But find out why you have no spark first or you're just wasting time and money.
And in the future, don't accept work on chinese junk. Most customers buy them because they are dirt cheap, not realizing that when they break, they are a money pit to repair because of parts and information being nearly nonexistent, unless you speak chinese and can call the manufacturer.