Got a new ST .90- gas installed on a great Planes Tiger Moth. Today I tried to run it. Can,t even get a pop out of it . Seems to suck fuel when choked but has never fired. Have 32 to 1 gas mix 8 oz tank open vent line on tank. 4.8 volt ignition battery 12oo mah. I tried getting a spark by grounding plug on head and cranking. Tried both by hand and with starter got no spark but while plug is grounded and I shut off ignition switch, I get one spark each time it is shut off. Needles are: high 2/1/2 and low 1/1/2 just like when I got it. Can anybody give me a hand? Any ideas or suggestions will be appreciated