I'm going to say that you are out of luck with regard to the original poster. He hasn't written anything here in a decade. There are still 20cc engines in production, but I think OP might have been a bit ambitious with wanting to try to cram a fuel tank and a smoke tank into a Hog Bipe. If you are doing a Hog Bipe you might want to consider modifying the firewall a bit to accommodate the size and weight of the engine but it should be doable.