^^^^seems about rightbsp (Box Stock Project) 196 clone engine is the best in Quality Control, and spec. tolerances control at the manufacturing facility, and was/is, and still currently Purposely imported for kart racing by Jimmy Simms/Box Stock Project..
Ducar, Dupor, same thing, they are good clone engines like the BSP, except without the Factory quality control, and specs to adhere to..
I would have to rate the BSP Top Clone Choice with 5 stars,
General Factory built Ducar/Dupor 4.25 stars
all the rest of the Honda Based Clone manufacturer's.. 2.5 stars.
That's just my personal opinion, & views on that question...