yeah my old ke70 was on straight gas and it ran good, it was installed by a gas company from new, so it had been on gas all it's life.
i can remember filling it up for 5 bucks and that wasn't too long ago.
there was nothing special about the engine, standard valves and seats, standard pistons, pretty much standard.
it done 278,000 km's before i pulled the engine out to put a 5k in it, and that ran gas until i sold it.