Hello! I also don't have marks on the fly wheel, but I looked it up on the WIKI and on you -tube It is quite easy to do.
First set your points to the right gap.
Then Find T.D.C. and put a mark on your fly wheel next to the split in the case ( I used the rear split as it was easyer to use)
Next make a mark 16 to 18mm to the left or right depending on your crank rotation of your modle
This is your timing mark.
I used a zenon timing light to get mine spot on.
I hope this helps.
( to all you out there who have been doing this for years sorry if not 100% but every one was a newby once. and I'm more used to 4strokes)