i have a honda 300 ex i just picked up. i only know the basics about engines and not much more.i had a gas leak problem on the carb were the floats were stuck and it was dumping gas,and then i found a crack in the tank. i was riding it and everthing was working till i seen the leaks and then i stopped.i then took of the carb off and replaced the pin for the floats and used some silicone on the crack in the tank. all this worked to stop the leak but when i put it all back together i can not get the engine to fire over.the neutral light is on and there is spark, im not sure about compression or how u know but i took of the spark plug off and put my finger on the whole and it blows air . i sprayed starter fluid in there and still nothing.i have a 2002 also and swapped carbs to see if that was it and it worked in the 2002 so i know its not the carb.i tried the carb from the 2002 in there and nothin.what could of happened? thanks for the help i really appreciate it the charge way to much at the shop id rather pay myself to learn.