issues with my kohler cv15

[38racing]

I've had it many years on a sears lt4000 ,using in winter with snowplow. I was getting it ready in November. It has the mechanical fuel pump that goes up over the engine. Normally after a long sit I need to spray carb cleaner in for a bit to get it running. That's what I did. I recall it was tempermental but it finally ran fine. I changed oil and filter and waited for snow. When that time came I could not get it started. Did usual checks, Had to use brake cleaner ( flammable version) to kick start. But it just seems to start and then backfire out the carb. I did spark test and got questionable results. 2 different spark plugs. Did the kill wire off thing . no change. Looked up coils testing and apparently kill tab to laminate should not be infinite but it was. Decided on getting a new coil. First test on new one have me an ohm reading on the test but after installing it symptoms are same except inline spark tester show a good spark. I pulled the valve cover. Valve action looks right with flywheel. Can't check clearance easy with the hydraulic lifters.
Did both compression and leakdown. Compress good. With flywheel near TDC and not holding it I got gauge up to 60 psi input , no hissing and about 6% leakage on the gauges.
While testing more of course a backfire had the excess brake cleaner flaming so I managed to melt the choke lever plastic so no hole for the choke rod.
I have the flywheel bolt removed but only see keyway of the flywheel , can't see the keyway of the crankshaft. Next step is pulling it but can't figure how it would shear after all these years of just running with a plow, no mower.

[bgsengine]

checked your exhaust outlet? Had one in that had a ground hornet's nest built up in the muffler, (amazingly enough.. I assume the freeze killed the bees, dunno..) It could suck, squeeze and bang but not blow..... but plugged with mud or anything else, could see same results...

[KE4AVB]

You won't see the crankshaft keyway as it uses a Woodruff key which is a semi half moon key.