I've had this kart since I was 18. Stretched the frame back then for my tall ass to fit on. Had an 8hp briggs, clutch driven chain, and don't remember what brakes. Did about 45 back then.
Then in 97 I removed the 8hp, and installed a Suzuki gt250 engine. On the motorcycle it would do 110, geared down on the kart to 65mph. 2 stroke, twin cylinder, 6 gears. Front brake from the motorcycle was installed on the rear axle. Twist throttle, hand brake, foot clutch, side shifter. Think it was rated somewhere around 40hp. Had to custom build a handle bar, and reinforce the rear frame/install mounts. Modified exhaust also.
1st and 2cd gear will spin the tires on pavement. 2in off the ground. Sounds mean as heck going down the road. But way to bumpy to drive off road much. Tractors are much more fun for off roading.
Over the years, it's bent a couple of axles, and worn out some tires. Biggest problem is keeping both cylinders running, keep losing coils and points. Two years ago I stole the axle from it for a tractor, and it sits. May one day put a 4 stroke ATV engine on it, if I find one cheap.
Here's a video of it at a tractor party couple years ago.