In my experience around hundreds of pallets with 800# of compressors bolted down to them, the 2" long staples shot pneumatically into them during construction took only a single good impact (wheels into a curb for example, if it's a gokart) to pull a little loose, making the whole thing twistably slipshod and liable to splinter up. If you must make a gokart out of a pallet, drill many, many holes in it, reinforcing every flat slat with long lag bolts thru big washers at each end and across the middle, minimum, and thru-bolt with machine-thread bolts and nuts on all of the frame structure.
Then you can figure out how to make a couple of inches of ground clearance work for you anywhere besides your asphalt street, if you can even make it across the gutter at the end of your driveway to reach the street in the first place. Wrap the grandkids in bubble-wrap for the inevitable bounce off of parked or moving car, truck, or school bus bumpers.
