Well, after my first and mostly successful wooden gokart, I decided to build a sturdier and better one. I used the same wheels, engine, axles, and seat from the first one. For specific details on mounting the engine, sprocket, and wheels, visit my first gokart. This is definitely an improvement from the first. For your convenience, I made a 3D Sketchup model. Download it here. The following steps contain pictures from Sketchup. I recommend you use Sketchup to find the exact dimensions.
Place a 22" long beam underneath. Do not attach. Next, place a 3 1/2"x3 1/2" in between the long beams. Place a 1/2" thick beam and attach it to the longest two beams. Then, drill down the middle of the 1/2" thick beam through all three layers. Put a bolt Into the and tighten. The bottom beam should pivot.
Attach a beam underneath the engine, and install blocks underneath that on either side. Drill holes through either side for the axle. Insert axle and and attach sprocket to axle or wheel then install wheels.