Revatu's boardtracker

I'm in love with this bike and I soon will write a poem, eeehhh arrange a photo-shoot. It's one of the best bikes I've ever seen. Revatu (Rene van Tuil) crafted this bike with his bare hands and he's is a hero! And the bike runs (and sounds!!!!) great! 3th place at the Bigtwin Bikeshow. What sort of engine this is? Try to find out yourself first :-)