Quick question on petrol flow

[Walterp79]

Please can I ask a quick question? My petrol gets to my carb, so the petcock works and the pipes are open. I cleaned my jets very nicely, so the carb is clean. But the spark plug is still dry.

I rebuilt the top end because I blew it. So the only reason I can come up with(and actually Jack came up with this) is that it's not sucking petrol because the timing is out. But I went through this so many times now I can time it with my eyes closed.

I also replaced the oil pump so I took the flywheel and magneto off at some stage. Is it possible that I could've done something wrong there so that the timing is still off? That riff key is there, so it seems like everything falls into place?

Silly question. If I turn the flywheel and look at what the valves do,it takes two turns to complete a cycle. Should it be one? I am struggling. 😂