Whats the best way to check for spark with an engine with no fuel source? I'm getting close to wiring up the mag and coil and want to kick it for spark. Is putting some Mystery oil in the spark plug hole and/or down the intake be good enough to kick it a couple times? The engine was seized when I got it but I was able to get it lose with mystery oil and gently rocking on the crank bolt.
Thanks in advance for help.

No fuel is necessary to check for spark. If it was locked up I wouldn't dream of it though, not without pulling the head and jug to have a look inside.

I agree that at minimum the top end should come apart. If it was seized before, although it may be loosened up now, most likely the cylinder has some corrosion that if not cleaned up, will end up taking out your piston and rings. Won’t take much time an will only cost you money for the gaskets.

Just kick you'll be ok. Plug resting on head. black from mag straight to the coil. Do in a semi dark shed to get a better look at the spark. Of course lifting the top end is best but i never do best & mostly get away with it. If it was seized "call it stuck' from long term sitting & not seized from melting piston or roasted bigend etc then i'd start it up. Did that on my HT1 & it was Very Stuck but came free with a bit of forcing on the flywheel with a special tool in the slots & lots of leverage back & forth. I guess the piston had just grown "alloy rusted" into the bore or rings had rusted to the bore. Anyway, ran like a new one but maybe just lucky that day. Important thing also is tighten that flywheel TIGHT. Look forward to your results. Oh--& make sure throttle is clicking right down. Piece of rope around the plug lead incase of stuck throttle. & if it runs on even with plug lead off then stick your hand across the carb mouth--or someone else's hand incase it hurts lol. Good fitting cover like off a spray can of similar size, that'll stifle it. Not expecting any of that to go wrong 'are we' so goodluck.

Thanks for the tips. I did take the head off and the cylinder looks pretty good. It has some compression with the carb off. I have gaskets and do plan to remove the the cylinder but first I just want to see if I can get a heart beat. If the electrical is not good, I will rethink this whole project. The bike as far as I can tell has just been sitting for a very long time with no evidence of water entering the engine. It also seems like it has very low hours on it. The head is very clean and most of the bolts on the bike show very little rounding. Did the enduros come with Philips head engine cover screws of hex screws? Mine are hex . That may give a clue to how much tinkering was done on this engine. The numbers match the frame. My flywheel puller just arrived so I will get that off ASAP and take a look. I just don't want to kick it over with a dry cylinder and damage anything.

Pretty sure the cases were fixed with Japanese Industrial Standard (JIS) screws - similar to Phillips, but different enough to cause damage to the screw heads when a Phillips screwdriver was used, not engaging properly and slipping.

This tool has become hard to find but will tell you if you have a good or weak or no spark.