I put upper end cams in my scooter and upped the upper end jet, but haven"t touched the lower end jet, it"s still stock, it is spitting back through the carb and will dye at times, after it warms up it doesen"t do bad , but untill it warms up good, it will even dye. It will dye at times even after it warms up! Im new to the forum, but thought I would try it out for advice. Thanks for any help on the matter!!!