I built a little gokart with one of those little 47cc Chinese two strokes last summer with my kids. It works pretty good, but wow are the carbs ever crude. We bought a couple used little quads, and I canabalized one of them to build the gokart out of.
I used scrap stainless tubing from work for the rest of it. Kristian
In reply to turbo_bird:
That's really awesome! Where did you get that seat? Our stock pedal car seat is proving woefully inadequate.
The carb, which is original to the salvaged motor, is pretty crude. A simple float bowl slide valve carb. The only adjustments are main jet, needle height, and idle speed. I bought an assortment of main jets on ebay...the jet that was in the carb was too rich.
Does your motor have a lot of compression? After rebuilding the motor, it has a crap-ton of static compression.....140psi. Makes it a bit hard to crank. runs very snappy though :)
We rebuilt the motor after taking apart what was left (basically a short block plus the intake). I soda blasted the cases and cylinder. Had to do one helicoil reapir on one mounting bolt. The crank, rod, piston assy and cylinder all looked excellent. The ignition coil was also fine. Parts purchased or replaced were: muffler, flywheel, pull starter and shroud, clutch assy, clutch drum, output sprocket and output sprocket support bearing. All told, I have about $50 in the engine.
Here's the motor after the rebuild, with lots of new bits:
The air cleaner is part of the salvaged bits. Someone tried to "enhance" breathing by drilling some random non-deburred!! holes (which drives my machinist OCD NUTS!!) in the outer cover.
At this point, the drive train layout was complete. All hubs machined, and a mockup motor mount created. Engine rebuilt.
That is the rear sprocket and caliper and brake disc from the donor minibike. Believe it or not, we're still running the original plastic axle bushings :) That will likely be a future upgrade. Because Spiral Development.
The seat that I used came from a child's swing set, I just took the plastic seat off of the metal frame. I didn't rebuild my engine (was run without any air filter) because I found a complete new one on eBay for about $80, including the gear reduction unit which the quad didn't have. Replacing the broken pull start and missing air filter, plus adding the gear reduction box was almost as much as the complete unit, so I figured now I've got some spares. I've never measured the compression, but even the one that was run without an air filter seemed decent. I don't think the carbs on mine have replaceable main jets even, I'll have to check them again. Kristian
This is amazing, the end result will be amazing, carry on
In reply to Rufledt:
Thanks. It's definitely been a labor of love that has exceeded my expectations!
Time to build some pedals:
Tig brazed:
Installed with a custom machined clevis mount with adjustable stops to manage pedal travel. I used existing bolt hole locations on the frame. I machined delrin bushings for the pedals to pivot on the mounting bolt.
Here's both pedals installed, painted and all cable attach hardware fabbed. The pedals are adjustable for travel, and I used standard cable adjusters.
In order to hook up the brake, I had to mount the brake caliper, which was donated from the scrapped pocket bike. I cleaned it up and rebuilt it:
Here's the motor mount I built. I slotted the mounting holes to be able to slide the motor assembly forward to tension the chain. At least that was the initial plan.
here's the completed power train. Ready for a bench test!
My 8 year old helped test out the engine and drive train...
Looks and sounds good. I assume the next video that played was yours too? How fast does it go?
Kristian
You will have the fastest lap to the mailbox and back in the neighborhood with this.....has McLaren contacted you yet 
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