It seems to me that 212 cc on a light weight trike (not a motorcycle-designed for highway trike) is way overkill. As mentioned before, 20 mph is more like it for a trike. They tend to tip over at speed. 79cc geared right should be plenty. Just my opinion. I'm setting my trike up for a 98cc Villiars midget, but it is an older 2 stroke of a putt putt kind of rpm range. Even so it is getting a heavy duty differential axle with a wide wheelbase and custom made wheels with fat tires, suspension front fork... in other words doing all I can to make it safe. Even so, I doubt that I'll go past 25 mph on a long straightway and a good bit slower on turns. Getting hurt is no fun.
SB