bitphire
You made a comment about starting dirt bikes and pulling the clutch in before kicking it over.
With the RE, the kick starter drives the engine crankshaft thru the clutch.
If the clutch lever is pulled in, the kick starter won't rotate the crankshaft. It will only rotate the output side of the clutch plates.
Bottom line is, when you want the engine crankshaft to rotate DO NOT touch the clutch lever while your kicking the starter lever.
Because the bike hasn't been started for a long time, putting just a few drops of oil down the spark plug hole (while your changing the spark plug to a new one) will help to keep the piston rings from scraping the cylinder walls.
It will smoke when its first started but that should quickly stop.
Also, after adding the new fuel (regular grade octane) it wouldn't hurt to take off the float bowl from the carb and wipe out the inside.
Before replacing the float bowl, turn on the fuel tap to make sure it's working and not gummed up. If fuel flows freely, push up on the float to make sure the fuel stops.
Do this a couple of times to wash out any crap that might have settled in the float valve. Then, replace the carb. float bowl.
After checking the carb and replacing the spark plug you should be good to go.
Have fun!
PS: These Royal Enfields have an old time transmission that takes long strong movement of the shift lever to get into the next gear.
The quick flick shifting of a dirt bike doesn't exist in this world.