I was given a mower that sat for 5 years. Put a new battery in, cleaned the spark plug but it seems to spin really slow and certainly not fast enough to start. Where do I start checking? I tried jumping it with my car after the battery got weak but got the same result... like the engine is bad. But I know it was fine 5 years ago.
Thanks!

5 years old is a lot of sitting, one thing to make sure is that it'll even start first, if it sat that long with gas in it, expect to rebuild the carb, its surely gummed badly from old gas, and change the oil as well...
What brand engine? Is this mower a sears? Poulan/weedeater? etc.
Bugs and mice love places like this, you may have a nest under the shroud cover, or the flywheel got so rusty, its holding onto the coil ( I've had it happen), or something's dragging, the drive belt or something isn't released... other then that, why did the previous person leave it sitting for 5 years and give it away?

Thanks for the help! It's a AYP from maybe sears or southern states. My mother-n-law gave it to me. She remarried and husband had a nice mower so hers just sit. It's a B&S motor. I'll start the process you suggested.
Rusty flywheel may be the key!

Since this is a b&s, it'll be pretty simple, is it a apposed twin? Or v-twin? In any event, after checking the coil and flywheel, just take some sand paper to the flywheel and coil, gap the coil with a dollar bill, paper or business card, till it comes out without ripping, but with some tugging and the flywheel doesn't catch. You may want to try and spin the flywheel by hand, just take one or both of your hands, and press down on the flywheel guard, and try to turn it (should get almost impossible when it hits the compression stroke) and just make sure it spins with relative freedom, not knowing if it is, but briggs did make regular engines with a cast iron bore, and of course the I/C ( industrial commercial) and the cast iron, when setting so long, can get moisture and rust a little. It could be a combination of things holding it up. Also when you pull the shroud, make sure the starter gear isn't stripped, if its worn out or indeed stripped, it's a cheap fix and worn ones can jam up to the flywheel and not catch the ring gear.

I finally figured it out. Needed a starter.
Thanks

Ah, yeah... though you could find a used or one online cheaper ( eBay maybe ) or rebuild the old one.