Hi, Go Kart Guru here, it is not my practice to advertise on this site,...but I felt compelled as critics can sit back in their arm chairs and rail at something they have not fully investigated, that I should at least defend the site.
First, no one is twisting your arm to buy this product. If you don't like it, send it back, it has 100% guarantee.
Second, I have had one guy complain about the product in the beginning, but then he put it into practice and said profusely "wanted to let you know that the vertical engine drive design that I previously complained about does work and wanted to apologize for coming off ungrateful.... So thanks for saving me the $700 plus for the clutch setup and the $300 for the horizontal shaft engine!"
There are issues with a vertical engine drive that need to be addressed, the vertical engine drive and accompanying books address numerous drive train issues to so that you don't end up frustrated and smoking components or spending a lot of money.