definite red face department, a series of events aligned with my ignorance:
1) The H1 leans a lot on its propstand, to the left obviously.
2) The alleged defective spark was on #3, the right hand cylinder
3) The H1F has a magneto style CDI
4) I'd been running the bike a few times to check voltages
5) The fuel tap is leaking and has a cup under it making turning on difficult, so I only turned it on occasionally for a brief time.
6) The fuel tap is to the left of the centre line of the bike.
All the clues are there...
The magneto CDI requires a firm kick or you don't get a spark, I was kicking slowly like a "normal" bike to look for a spark.
Since the fuel tap was leaking and difficult to turn on because of the catchment cup I frequently didn't bother.
I'd run it a few times to check voltages and drained the carbs. Turned the fuel on briefly which filled #1 and #2 but didn't give it time to fill #3
Because of the lean angle and the fuel tap location it takes longer for #3 carb to fill.
... it was sparking fine, there was no fuel in the #3 carb.
