Outdoor Power Equipment (Lawn Mowers, Snow Blowers, Chain Saws and more) Discussions

I have a 12.5 hp I/C  Briggs on a riding mower. When I started the mower it fired right up but was running roughly like it had no power. I throttled up and down a couple of times to see if it would even out and it didn't, so I took the air cleaner off and throttled up and down again and I got a puff of white smoke out of the carb. I could not get it to turnover at all after this. I figured she just blew so I walked away. Knowing that I am very consistent with keeping the oil changed in this rider I started back at it today. If I take the spark plug out it cranks over fine and has compression out of the spark plug hole. When I lifted the tractor to check the underside I found a piece of fence wire on one of the blades. Did I shear the flywheel key or where should I start?  thanks.

How old is it?....What model of Briggs is it?  Does it still have compression?

Friiy