Ignition timing

[Bretty]

As everyone else said. You're right, cylinders spark on exhaust stroke and compression stroke, obviously only compression stroke fires as there is fuel.
Check all the dots and the 'T' on the crankshaft line up perfectly!! If any of them are one tooth out, the engine will run ok, but isn't quite right. I remember doing mine and it wasn't quite perfect. And it bugged me so I took it all apart again until it was spot on. It will and should be spot on!