How does this engine work?

I have a mini moto engine which i'm going to use to power a go kart type thing. I need help identifying the different intakes as it looks like there are three holes. I think the middle one is to attatch a throttle cable, but what of the other 2? One already has a pipe attatched to it (right hand side) and the other (left) looks like it has a fuel tap. I'd guess fuel and oil, but I always thought that had to be premixed, so shouldn't there only be one hole? Any help in identifying the different bits would be appreciated.

Picture of How does this engine work?
Burf5 years ago
From left to right: fuel inlet...throttle cable port...fuel overflow line
frollard5 years ago
see also: