Small Engines (Lawn Mowers, etc.): Hard to crank, lead acid battery, sealed lead acid battery

Question
Michael,

I have finally decided to address the hard starting of my 12 hp DR chipper with electric start. I replaced the wimpy sealed lead acid battery it came with and installed a much larger normal graden tractor battery with 230CA and I also changed the small wires with new 2 gauge wires. I expected the motor to spin and start but to my surprise, it still does not turn over. Goes about a 1/2 revolution and stops. As I stated before, it is also very hard to start by hand and ripps the cord from my fingers. I checked the clutch on the motor that drives the chipper and it is fine. I kind of think it might be a failing compression relief but I don't know how to test that. Any thoughts?  

Answer
Hi Jim,

I suspect a partially sheared flywheel key, which would advance the timing, causing a kickback.  This is common with a push mower after hitting an object with the blades.  Maybe  the chipping action caused the same result.  Especially if the chipper is direct drive with the engine.  
If the engine has points you could adjust the timing with them.

Let me know how you make out.
Michael