Let me put it in a way that you should be able to understand. When you take a hit off your bong, if you don't put your thumb over the clear hole, you have a giant air leak and you aren't going to suck in very much smoke and you're not going to get stoned. It's the same thing with a 2 stroke. If you have an air leak because of cracked intake boots, leaking reed gaskets, or leaking base gaskets, you're sucking in straight air, instead of air mixed with fuel and OIL, and your motor will turn into a brick.