Man, this thread is so fascinating as I have never done nor seen a gas conversion after 20 years in the hobby. I gotta try it. Are there any step by step guidelines or instructions on converting to gas / ignition ? The piece about just running a big ST just by putting gas and oil in it is unbelievable to me. Couldn't be simpler. How do you measure the oil percentages mentioned ? Thanks to everyone who has taken the time to answer my dumb questions. I'm thinking now about a ST 90 conversion. I have written to APT at this writing. No rersponse yet. Thank you.