What is the gap of ignition module of MTD 31bs63bd516.regards

The ignition module is underneath the blower housing recoil starter. Remove whatever you find necessary to get to the blower housing.

Air gap is 0.016 to 0.020 and mounting bolt torque is 80 - 100 lbin. Do NOT over tighten as threads in block easily strip.

See following for more detail.
https://www.mymowerparts.com/pdf/MTD-Service-Repair-Manuals/MTD-Big-Bore-Engines-78-277cc-83-357cc-90-420cc-Repair-Manual.pdf

Hi...
I have replaced a number of Ignition Modules in chain saws, lawn mowers, etc. and the one trick that solved the problem of setting the Gap Setting, was to use a "Business Card" in between the Ignition Module and the Flywheel. Just curve the Business Card around the Flywheel magnets, and press the Ignition Module firmly against Business Card and tighten down the holding screws. Then pull the Business Card out, and the Gap Setting is perfectly set. Easy and it works every time.
Rayko

The ignition to flywheel gap is not hyper critical. A .024 will not stop the engine from running. Evidence is - you are getting a spark. You could lower it to .015 and maybe get a better spark.
Are you getting gas ?
Remove the air cleaner and spray a quick shot of starting fluid into the carb.
If it runs for even a little bit, your spark is not your problem.
I'm betting it will run.
If it runs for a bit, clean your carb.

The gap should be 0.3mm.

ignition module gap is generally 0.25 feeler guage

You need to use a thin business card to set the pole gap at the module--access the flywheel/module area again and turn the flywheel magnets under the module poles. Insert a thin business card into the pole gaps, loosen the module mounting screws and allow the module to contact the magnets. Tighten the screws and rotate the flywheel somewhat to release the card. Rotate the flywheel one full turn to make sure the gaps don't close up any further. Remove the ignition switch wire from the module body for a test, and try for spark--it should be blue and snappy on a clean plug gapped at 0.020". Hook the ignition switch wire back to the module. Hope this helps!

I assume that you have already tried a new plug (gapped 0.020") with no results. Remove the left case cover to expose the flywheel and ignition module. Remove the ignition switch wire from the module (not the one tied to the module metal frame), and try for spark again. Check the module pole gap with the flywheel magnets just under the module poles using a thin business card for a gap gauge. Insert the card and loosen the module mounting screws to allow the module to contact the magnets, tighten the screws, and turn the flywheel somewhat to release the card. Turn the flywheel one full turn to make sure the pole gap doesn't close up. Test for spark again--if still nothing, replace the module using the same gap method. Hope this helps!

Eigther the kill switch failed or ignition module. Disconnect wire to kill switch if you get spark then switch is bad. Still no spark with kill wire disconnected ignition module quit.

Remove the starter mechanism and the left side cover to expose the flywheel and ignition module. If you have little or no spark, try setting the pole gap using a thin business card for a gap gauge. Turn the flywheel magnets under the ignition module poles, insert the card into the gaps, loosen the module screws and allow the poles to contact the magnets. Reset the screws and try for spark. Hope this helps!

With out the model # of engine or plug not 100% certian but 99% of those mower engines run a .8 or .9mm plug gap you will be preety safe setting it at that

Regards
Brad