I raced "Briggs stock heavy" on the former local road course a few years back to wean myself off racing after quitting motorcycle racing cold turkey. Sort of Nicorette for racers in my case.
Stock at the time meant you buy a couple new Briggs & Stratton Motorsports Raptor flatheads and have the local engine builder blueprint them to the fullest possible extent of the rules, and possibly then some.
They run on methanol, make about 10-11 HP, and rev to close to 7K rpm.
You change the oil after practice, after qualifying, and after the main as it gets contaminated w/ fuel which is corrosive and hygroscopic. They ran at 360#. and what with me being an actual size adult I ran zero ballast and partial bodywork to make weight.
Cheating was pretty rampant; Now and then the kart in front of me on the grid would be started a minute before the qualifying heat went out and the nitromethane fumes from the exhaust would practically blind you. The physicality and violence of circulating the .25 mile 10 turn super rough track would leave you sore 'til Tuesday every time. The firld was usually the same 6 guys that had been racing one another since the Carter administration and they were in effect, unpassable.
Setup is completely counterintuitive; the inside rear wheel absolutely has to be in the air on corner entry to be competitive - you do this by monkeying with track width, tire pressure, axle diameter/stiffness, and above all - CASTER.
The upside is of course that it's incredibly fun racing, you will frequently be in contact simultaneously with 4 other karts; front, rear and both sides - the track food was excellent and cheap, and the people were either nice or crazy hillbillies and nice.
I was sad when the track closed and sold off all the 4-stroke stuff but kept a mid-90s Margay Cougar and a couple Yamaha KT100 2-strokes. SCCA won't let me run in the kids class even though that's what the kids run, but I may buy a seat and tires and go play just for fun next season.
Karts are great, particularly if you live someplace other than an urban center where there's karting.
It's a ~15 year old Invader with a 5HP Tecumseh engine and weighs less than 100Lbs. I had to rebuild the carb, replace the primer bulb, replace the throttle cable, new spark plug and fuel lines, and fix the inner tubes. I put a few miles on it today with a HUGE smile on my face! And then the clutch broke...
