I don't tune my oeds off heat range, yes it is in mind but I dial in my carbs with a AEM wideband. Getting the air fuels at WOT between 12.5 - 13.5. My guess would be that if he has a 70 cc piston kit that his air fuel ratios would be lean with a jet size of 70, but I'm not there and he doesn't have a wideband to check his air fuels that I'm aware of.