These are interesting engines. The cylinder and head appear to be yamaha inspired. They have a pretty decent 3 transfer cast iron cylinder. They have a pretty large exhaust header, and come with a nice quality mikuni carb (although it's tiny). The reed valve uses the 4 bolt pattern shared with polini/tomos/peugeot 103. The clutch and clutch bell are pretty much the same design as the tomos A3, although just a tiny bit larger in diameter. The downside is that the transmissions aren't very robust.