What we are going to focus on here is getting a bike started that has not been run in quite a while. It might have been sitting for 10 years, or you may have no information about the bike at all, whatever. Don't be daunted! Its really not all that hard.
First off, take a look at the following picture, and let me know what is wrong:
You got it, eagle-eye. The boot from the plastic airbox to the carburetor is missing. Air is flowing into the carbs without entering the airbox first. I see this type of stuff ALL THE TIME. Guys think this is no big deal, or I will go through all this diagnostic help with someone over the internet, and we still can't figure out what's wrong, and then finally they just sort of casually mention "oh yeah the airbox is off, I was going to wait until I got the bike running to put the airbox back on. Is that a problem?"
YES. It is a problem. I don't care if your cousin's nephew's best friend's priest has a dirtbike that can run underwater with no airbox on. The vast majority of motorcycles require that everything be all assembled correctly and tight in order to run. This means airbox is connected and air filter is good, not damaged, and installed properly. Boots are good and the clamps are tight. Exhaust is tight. If you have holes in the exhaust or straight pipes that is not as big of a deal as holes in the intake, but seriously we need to put the bike in a condition for it to function before we can determine what is dysfunctional about it. So please take the time to correct any of the previous owner's mistakes, and repair/replace damaged intake parts, and assemble them before trying to figure out what is messed up.