I have the same problem with a Clark CGC70 w/ Vortec. I posed the question here awhile back as when you start cranking there is no spark for the first couple of revolutions on the crankshaft meaning seriously extended cranking time before the thing will actually fire up. I was told this was to prevent pre-mature ignition or some such. I seem to remember some horror stories posted about blown valves and such. I told my operators to deal with it but it's **** on battery life.

doesn't this unit have an oil pressure safety switch, and requires engine oil pressure to build up before the ignition gets spark? you might try checking and changing the oil and correct oil filter (not the cheap store brand, but get OEM or better quality filter, as the better quality filters will have check valves that can help hold some oil and maybe even pressure in the filter), using the correct spec oil, getting a battery of the correct cranking amps so that the motor spins fast enough to build oil pressure.