Small Engines (Lawn Mowers, etc.): Craftsman 6.5 lawn mower wont start, briggs stratton, second person

Question
Hi
I have a Craftsman 6.5hp Briggs & Stratton lawn mower.  About 1 month ago, I hit a tree root.  The motor shut off and the blade bended.  The mower did start back up and as expected the grass was cut uneven.  

Today, I replaced the blade and tried to restart it.  But the mower won't restart.  The pulley sometimes pulls back forcefully.  I tried loosening the blade slightly but no luck.  Any suggestions, would be highly appreciated.

Thanks in advance,
 Jorge


Answer
You should check the crankshaft to make sure it is not bent.  Remove the spark plug.

With the spark plug removed, have a second person tilt the mower with the handle on the ground.  Have the second person squeeze the engine shut-off handle and pull the string.  As they pull  the string you watch the blade.  If it appears to wobble the shaft is bent and the mower will not run.  A bent shaft usually means a new mower.

If the shaft is straight, remove the blade and blade adapter and check the key and adapter for cracks.

If that's alright then the flywheel key is sheared.  You need to remove the fuel tank and top engine sheet metal cover to access the flywheel.  Remove the flywheel nut and flywheel to replace the key.  You will need special tools to remove the flywheel...a flywheel puller.

Let me know if this helps.
Eric