19.5 Briggs Stratton Twin Hard to turn over and wont restart after running

I have read many post on subject of this motor not wanting to restart after running. Most point to problem with Magnito/coil. I replaced with new one and thought I would be in clear. Second problem, I was unable to find out if problem fixed due to problem with engine not turning over to start after turning off. This has been a long time problem with this mower. Replaced batteries couple times. Frustrated I purchased small car battery and squeezed it in. Thought it would spin like crazy. Still struggles a little but spins enough to start. Brings me back to original problem. Now that it spins over after turning off. Does not start. Starts good when cold. Will start up after it sits for a while. Please Help!

Without knowing model number I am assuming opposed twin. It sounds like you may have two problems. A poor connection some place, possibly a poor ground. Could also be caused by undersized battery wires. This engine was also known to have a starter that is somewhat undersized, couples with also having to turn over the tranny in some cases. You will also need to remove both spark plugs, and crank the engine to check for spark when you find it won't restart.

If you find you have spark make sure the other spark plug is hooked up and recheck, because I have seen this module fire when 1 plug is connected but not both. Due to an internal short.

Hey, Thanks so much! Yes opposed twin. Got you as far as starter goes. As mentioned, I just installed new oversized battery. Im gonna upgrade batt cables and check and clean all connections from battery to starter. I know from working on boats that 99% of time when there is a electrical problem it has to do with ground. i'm confident I will beable to spin motor over if those are inherent problems with spinning motor over. No OHV's to adjust. Next step will be to get the darn thing to start.
I'm gonna try to follow along with your suggestions for this problem of starting. Just to give little more history. When cold or not recently running. Damn thing fires up like a champ. Only after its been run does it give me problems. This in most blogs I've read in is atributed to the magnito. so I bought after market one and installed it. It was identical to the old one with exception of it having two grounding wires. I simply iliminated one, set gap at index card thickness, cleaned flywheel surface, and fired right up. Skipping ahead to attempt to re-start. I did pull plugs to check for spark. BUT, for what ever reason I did them one at a time. First pulling left side, spun over, saw spark, re-installed and went to right side. pulled the plug, spun over, saw spark and BLAM. She fired on one cylinder and started running. I quikly shut her down. Re-installed right side plug and wire, checked all connections and attempted to start. Wa,Wa,Wa (pac man dieing sound) Spins over but no start.
So, you mentioned one side sparks but other does not? I think we are on to something here. What next? Sounds like when attempting to re-start, pull both plugs and check for spark at same time.

If you have fire with one plug connected but not both then that is an indication of an internally shorted module.

Ugg. Thanks for your in put again. Not sure how to interput your answer to what i did. Had one spark plug in cylinder and other out of cylinder. Plug out of cylinder was connected to plug wire and resting on intake maniflod. Spun over, had spark in plug out of cylinder. Did not start when spinning over, but did not expect it to. Put that plug back into its cylinder and pulled plug from other side. With plug connected to plug wireand resting on manifold, spun it over, i was able to see spark, and then the engine started. Running only on the one cylinder in which i had just check and returned plug into. I turned it off. Replaced the plug, checked all connections, spun it over and nothing. This is exact symptoms of problem that existed with the previous coil. Not totaly unbeliveable that new coil could be bad as well. Just seems odd. As if chaseing different problem.
Im quite certain that you have better thing to do than sit around and attempt to cyber fix my mower. I appreciate your help and in put. Do you have any suggestions for further diagnostics? Just let me know when your tired of answering my questions. Thanks again!

And just because it is a side banger, that does not mean you do not have to adjust the valve clearances .
They are a PIA to adjust because you either have to shorten the valve stem or cut the valve face &/or seat.
OTOH they don't go out of adjustment but they do wear.