I must emphasive safety first. I would feel horrible if you attempted this modification and you or your child got hurt. If you're not mechnically inclined, get a buddy that is. This project takes some creative thinking and understanding of physics.
I used what I had readily available from the dumpsters at work, yard sales and in my spare hardware bins. Any extras I have purchase are readily available at Harbor Freight, Northern Tool ,or Ace Hardware stores which I've listed in the next step.
Update: January 22, 2013
Littledude isn't so little anymore and prefers to be called Kuhldude (pron,"cool-dude"). He was a little upset when "Meepers" was dis-assembled so i started mentally designing a go cart. I found a "Jazzy-Hover Round-Mobility" scooter, and started hacking! I've attached a video. It is still a work in progress
Step 2: Tools, Parts and Supplies W/ (costs & Source)
Power tools: Rotary tool w/ a variety of bits, drill w/ jobber bits (Ditto above)
Portable Drill: ($18 from Harbor Freight)
90 Degree Drive w/ chuck: ($10 from Harbor Freight)
Adjustable vice (I already had it but its not completely necessary if you have a buddy to help you.)
Kick scooters, any type ($3 for one and the second was free, both from yard sales)
Metal rods to be used as replacement axles (Free, recycled from a dead desktop printer)
Angled bracket (Free, dumpster dive at the local recycle center)
Metal banding clamp (preferably with a screw type adjustment) (Free, left behind by previous owners of the house)
Heavy duty sprockets (Free, I recycled mine from a dead business shredder )
A 2 to 3 inch nail (Free, left behind by previous house owners)
Tool Dip ($8 comes in black, red, yellow and blue from Ace Hardware)
small piece of sheetmetal approx. .060" thick (Free, was one of the printers' box / frame)
Fiberglass Kit (Free, from left overs at work but there is a decent size kit at Ace hardware for $20)
Heavy rubber disc (Free, recovered from the recycle center.)
Bicycle brake ($8, from Walmart)
Step 3: Basic Assembly
From the rods out of the disassembled printer, the extra bushings from the other scooter and the 90 degree drill driver, I cut out the necessary space to accomomdate the wheel offset outside the rear wheel cutout mounted on the rod/ axle.
I fashioned a holder from fiberglass and resin for holding the cordless drills. I added a rubber piece too isolate it from vibrations and attached it to the 90 degree angle drill adapter.
The throttle/ drill trigger is activated by pulling the lever on the handle which squeezes the brake pad. I mounted this brake caliper on one of the rods and positioned it to press the trigger by putting a bend in th rod and tying it to the bracket with another banding clamp.
Step 4: Drive Wheel Installation
Assembly with the larger wheel required I offset it or I would have had to cut into the scooter wheel well. I accomplished this by using bushings from the old scooter and put them on the outer sides of wheel slot to stop the side to side slop.
Step 5: Fine Tuning and Adding Flare/ Bling/ Graphics
Finally I coated the deck, fender, and angled bracket in Tool Dip. It is basically liquid vinyl that has a solvent that evaporates but it can get messy and very sticky very quickly. I glued a small piece of rubber foam over the front edge of the fender and added an electronic horn. It makes an annoying "meep meep" sound so Little Dude calls the scooter Meepers.
Graphics and upgrades are going to come later since Mom and I are in the middle of a garage re-modeling.
I was able to keep my cost to about $50 and Little Dude can go at least 5 mph so I am calling it a success.
Thanks for checking out this instructable and I hope you get some good ideas from it for your project.