Finally got my 5hp running but know it will not go, it revs up but there no low-end torque to get going. also when you do get to higher RPMs it starts to backfire. but it will idle fine, the wheels will spin, and the oil is fine. pretty sure the F/A mixture is right. Could it be my Gas tank/Carb seal letting to much air in. Or maybe my fuel jet?

Check your flywheel key to make sure it isn't sheered. Make sure the air filter is clean. Try it without the air filter also. Have you replaced the spark plug ?

yes just changed the spark lug today. also i AM getting spark so thats not a problem. and the oil smells like gas. i read that that means i coudl need a new needle valve. or and oil change. opinion?

Yes i would change the oil. And use 30 HD oil. Just because its sparking doesn't mean the flywheel key isn't sheered. If its electronic Ignition then it will just fire out of time. Is your carb the type that mounts ontop of the fuel tank, or does a fuel line run from the fuel tank to the carb ?

Is your carb the type that mounts ontop of the fuel tank, or does a fuel line run from the fuel tank to the carb ?

its the kind thats on top with a fuel line going into the tank connecting to a fuel filter.
also it is a pull start.

BTW Engine Model:
Model: 130212
Type: 4006 01
Code: 91120407

if you have gas in your oil, you definatly need to replace the needle and seat, it is flooding, and that could be part of your problem.

and also do what phillip said, you might have had enough gas in the oil that the motor kicked back a little bit and marked the flywheel key