I am running mine on 16:1 synthetic without problems and it uses the stock bushed rod. I have converted both the older S90 and the newer G90 with equal results. My ST51 is still using the glow carb but the 90 has a walbro on it. All of the ignition components, including the hall effect mount, came from Bill at CH Ignition. Great guys to deal with and there are no better ignition products made IMHO.