Timing is everything, as the actress said to the Bishop . . . if you have compression, a fat spark and fuel, timing is the next thing to check. You don't even need a lot of compression for an engine to fire. I had a VW powered offroader many, many years ago in my yoof and it only had 40 - 50psi when i did a compression test. It fired up and ran like a champ . . .
Don't need a lot of compression. But if compression is low, that might point to something like a burned head gasket or valve. problem there is not the loss of compression, but that on the intake stroke it pulls air in through the leak, causing a very weak mixture. Have you tried a squirt of Start y Bastard ? Doesn't always do anything but sometimes it does the trick (really good on sulky two strokes) . Which could fit with 8 stroking, which can be casued by either rich or lean mixture. In a very lean mix, the mixtures too lean to fire on the first stroke, but on the second, the fuel left unburned from the first stroke is added to that of the second stroke, and that's rich enough to fire.
Jaycar have a great little book "how to use your mulitmeter" for less than $10
