Change the Earl
Go Kart Oil Maintenance
Changing the oil is easy, cheap, and often neglected. Doing it on a schedule will add to the life of your kart's engine.
First, check the oil level each time before riding. Generally it should be visible at the bottom of the filler cap threads.
How to Change the Oil
There's a few ways to do this. The first is the easy and dirty way, and the second is the hard and clean way. Oil will flow better and you'll remove more sludge if the engine is brought to operating temperature before changing the oil. If done this way, use caution because the oil will be very hot.
Easy Way to Change Oil
A Briggs engine will have a square-headed bolt at the very bottom of the block. This is an oil plug. By unscrewing this, the oil will flow from the lowest point on the engine — helping ensure you get the sludge out.
Unfortunately this means that the oil flows out all over the mounting plate — and hopefully then into your oil catch pan. Clean up time!
Harder, Cleaner Way
You can remove the engine and dump the oil, but this isn't really possible if you heat the engine first, so the flush won't be as good. Or, you could remove an oil-filler plug and tip the whole kart backward on the back bumper, dumping the oil into a carefully positioned pan.
You should change the oil according the engine's specifications. Briggs recommends changing the oil after 25 hours or once per season. Considering that karts go more action than lawn mowers, try to adhere to the hours usage.