I bought my bike use, so I'm not sure what's been done to it. I have slip-on... How do I know if it's running rich or lean? I'm pretty sure it's an old race bike (everything is safety wired). It's runs ok for me, but I'd like it to be at it's best... not sure if I should get a jet kit or not. Is there any way to tell?

 

Check your spark plugs.

Take your bike for a nice long ride and get it up to temperature, then hurry home and shut off the bike without letting it idle for too long.

[ul][*]A light brown spark plug tip means that yourbike is running fine: not too rich and not too lean.[*]If the spark plug tip is wet or really dark, you're running too rich.[*]If the spark plug tip is white and burned looking, you're running too lean.[/ul]
Exhaust popping on engine brakingis also aside effect of lean conditions.

 

I guess it's not lean... no popping. It doesn't smoke or reek of fuel when it's running...