Turning over pertains to what the flywheel is doing... if the flywheel turns, it is turning over.

If the engine is cranking over/turning over but will not run.... is is turning over but won't start/fire.

Remove the spark plugs... rig a spark tester to see if there is spark that will jump a 7/16" gap with a strong blue lightning like flame... a real SNAP! The gap is important!

If you have compression and spark, read up on the starting procedure. I assume that it has a priming setup instead of a choke?

Yes it is turning over but not starting or even beginning to. I replaced the spark plugs. It has a choke for the start up.

First, make sure the spark plugs are firing...GET A FRIEND TO HELP - take both plugs out(easier to pull the engine over).. take one and put it in the spark plug wire(make sure its seated in the cap).. lay/holding the cap -hold the spark plug against the head while turning the engine over(making sure the hex of the spark plug is making contact with the metal part of the engine)... it should have a blue spark across the gap.. if you do not see a spark.. make double sure you are grounding the spark plug against the engine while your friend tries to start the engine...no spark..no run! If there is a spark..NEXT.. spray some WD-40 into the spark plug holes...install the plugs... it should try to run or run for a few seconds... if it does then the problem is fuel delivery (clogged carbs)... take it to a good mechanic...(any good mechanic - a really good motorcycle mechanic) should be able to clean and set the carbs,,they are not that complicated!! If it won't start at all... it still could be a fuel delivery problem. NEXT - check the compression (without a gauge - wet the end of your finger and hold it tightly in the spark plug hole (seal the hole) - (KEEP THE SPARK PLUG WIRE AWAY - IF YOU DON"T YOU MIGHT FIND OUT THE ENGINE IF FIRING THE HARD WAY!!) and have your friend try and pull start the engine.. it should blow your finger away.. if you can hold your finger in the hole without the compression blowing your finger away.. you need to proceed to a better compression check with a gauge - it should pump to a minimum of 100 -110lbs. with the throttle wide open... and pull the engine over 4-6 times QUICKLY before taking a reading. IF all of these tips are ok..contact someone that can "hands-on" diagnose further.

Good Luck!