Small Engines (Lawn Mowers, etc.): B&S 5 h.p. engine, horizontal shaft, digets

Question
i was given a go cart with a B&S 5 h.p(135616 is the model #i believe) engine on it the cart had sat for 6 years with out being ran. i emptied the gas and oil out and put new in for both, replaced the gaskets, cleaned the carb out, removed carbon deposits,put a new spark plug in and it had good spark, and then went to start it..at first it started then died out within 3 seconds, did that a couple times then wouldnt start at all so i recleaned the carb. then tried to start it agian. it wouldnt, so i checked the carb and there was gas inside of it but where it meets the engine block to come threw the valve it was dry, and when i had the air filter off and started it a burst of air shot back out of it, so i made sure the valves were sitting properly and they seemed to be sealed when there suppose to be threw the cycle. so i dont know why its doing that or if its suppose to do that...but the engine wont start...if you have any suggestions id greatly appreciate it...thanks

Answer
I have had defective spark plugs cause this problem...even a few brand new plugs right out of the box. So, I'd try another new plug.

Check the engine code number.  If the first 2 digets are 81 or higher then you should have electronic ignition and as long as you see spark then the igntion should be fine.  If those digets are lower than 81 then you may have points that need to be changed/cleaned.

I would also check the flywheel key.  They rarely shear on horizontal shaft engines but I always check.

Did you remove the cylinder head?
Does the engine have compression?  You can rotate the engine counter-clockwise and if snaps back then you should have enough compression.

Let me know what you find as well as the answer to the questions.

Eric