Agree you are on the large side (okay, WAY on the large side) for kart racing. All those little guys you pushed around on the football field in high school? This sport is their revenge. If you want to stay 4-stroke, look at the Briggs World Formula. Much stronger than a chronda or L206. Pricier too, I’m afraid, but as a drag racer I’m sure you are familiar with the proportionate relationship between $ and horsepower.