Has anybody done one of these kits, I am interested , but want something reliable (more than 3 or 4 dune trips)

 

I wouldnt even consider either engine. They are unbelievably slow for there size and will not likely last. I would recommend going with something like a 420 or 410(5mm stroke or 7mm stroke). That would be fast and and probably give you good service. The 410 is very reliable and would be my choice. Try Port MAgic for a builder. Rudy does a great job.