Riding Lawnmower Not Starting?

I was reading a post that said;
"On the top of the engine is the air intake screen. With your hands move the screen in reverse or counter clockwise until you have resistance to the turning. Stop and try starting the mower. It worked for me. So every time I want to start the machine I have to counter turn the air screen untill I feel the resistance. "

I tried this and it sorta worked, but it only turns the engine over partially and it locks up again or stops trying to start.
Why?