So I bought a 2012 Coolster 110cc, I believe. I picked it up for cheap this weekend. The problem is that the kid left it outside for at least a year with no spark plug. The motor is free(first thing I checked).

What should I do?

Do I try putting new oil in it and see if it runs?
Do I vacuum out inside the cylinder first? Or just let it burn out whatever is in there?
Do I put some oil in the cylinder first?

Or would it be best to buy a new piston/rings from the beginning and possibly try to save the cylinder?

It is a 3-speed with reverse so I think it's still worth it to fix since I picked it up so cheap.

 

There can't be too much rust on the bore or rings or it wouldn't turn over. Spin the engine over a few times to blow any dead spiders etc, out. Pour some oil down the plug hole and spin over again, Fit a new plug plus fresh engine oil and see if it fires up. If you have no compression, it is more likely to be a stuck valve than a rings problem, but you may need to remove the head to free it off, so can check the bore/rings then. One other thing, he took the plug out for a reason, you could find that there is a fault that needs fixing as well.

 

If it sat that long, flush out gas tank, take apart carb, clean and blow out jets, put inline gas filter. Just don't let it become a money pit.

 

Thanks guys! It seems to be running! Although pretty rough, it is running. Going to run a little seafoam through it and I will clean the carb again if it doesn't clear itself up soon.

Did the regular non-running fixes: cleaned the carb, new spark plug, fuel filter, checked for spark, etc.
First thing I changed the oil. Then I dumped a bunch of oil in the cylinder, turned it over a bunch of times, and then used a shop vac to remove some of the excess oil. Then fired it up. Didn't take much either.

Thanks guys!!

 

First thing you should have done before turning it over is dump some diesel down the cyl. This would have lubed everything up and dissolved some of the rust. Then dump it all out and put fresh oil in. By turning it over dry the way you did any rust and dirt in the cyl you have probably scored the cyl. So it may need a freshen up sooner than later. Putting regular oil in the cyl helped some but with the rust and dirt it probably did not make it down around the cyl... ATF works great as well