Thanks for the kind replies. I first had a 79cc Greyhound on it-and it was a really nice running bike. But I sold my Trail Horse roller and had the left over 5.5 just sitting there. The 79cc,at first,went on my Monster Frijole build-then I decided to use my 99cc Predator with the AGK race carb and header for that. So I halfway assembled the 5.5 on the Sprite to see how it worked-and everything JUST fit. At first I thought otherwise,but today I was bored after putting up Christmas decorations all morning. So I basically put on the chain,throttle,and tightened the engine bolts-just to try it out. Well,it really flew!! The frame IS small-but not tiny,like a Lil' Indian,for example. It was originally designed for younger,beginner-level riders. So a big motor is fun,but not scary. Here is a picture of the bike with the 79cc for comparison.
You can also see the 79cc version on YouTube-just type in "Orange Sprite Mini Bike". As you will see,it wasn't exactly slow......