when you get the white bomb and shut it off, if you restart it do you get the white bomb again? If NO, then I don't know how "gas in oil" cleared itself up.
I've had the white bomb myself and it was leaky carb with no fuel shutoff that was leaking while not in use, then when started white bomb always AND oil level was well above the full mark. it doesn't sound like this was your problem. If engines runs OK for periods,
there is no gas in the crankcase - if there was, you would get WB all the time.
Therefore, if it is WB from "gas in oil", then it has to be coming from the carb in 2 second bursts. But could that fuel dumping produce the WB as if gas in oil?
Thinking... why white bomb when gas in oil? Has to be oil on the cylinder walls gets burned producing WB. So if WB occurs when running, huge amount of gas must be dumped from carb. (Can't be the fuel pump because it couldn't leak the amount of fuel into the oil to produce that washing on the cylinder walls.)
Thinking... there is a loss of power. This could be like the engine was choked due to a huge amount of fuel coming from the carb. Does the loss of power seem like choking? If it runs good and you choke it, do you get the WB?
Thinking... the amount of fuel that dumps out of the needle/seat when float low is not a torrent, it's more like a dribble. But if the bowl is full and the float is closing the needle, if a leak, it has to be much less which doesn't quite explain the WB even if full needle discharge would be enough fuel flow to create WB.
Is there a possibility the float is sticking? did WB occur when you ran over something that shook the engine OR hit a heavy patch of grass that put big load on engine?
STICKING RING: Automotive Engine with bad rings will WB when under full load. But the 2 second duration is not quite consistent with this cause, however could be something small engines do.
Maybe my thoughts will give someone an eureka moment?
