I was driving it one nite and it died just like it ran out of gas. So i took it home and cleaned the hole carb put everything back togethor, and started it and now it is knocking really bad. SO i pulled the plug to what it looked like it was wet and black. I put a long skinny screwdriver done the spark plug hole and turned it over didn't feel the piston move so i think the piston or rod is broke. It still turns over fine and sounds normal till it fires up. Would you actually be able to reach the piston through the sparkplug hole?

 

First off. If it cranks, the rod is not broke. The only thing I can think that could tie these together is if you were riding hard, and up into some higher rev's while low on oil. You may have fried (or broke) your piston rings allowing the piston to rock in the cylinder causing the knocking noise or ran the rod dry without oil for only a few seconds. That will desroy a rod and crank, also will cause a noise like someone is hitting the motor with a hammer. Either way if the plug is oily you may have major engine damage.