I bought this Chinese replacement carb https://www.amazon.ca/Cozy-Carburet.../dp/B00KYK1RZI/ref=cm_cr_arp_d_pb_opt?ie=UTF8 for my Grandsons CC100 bike. It has two adjustment screws on it. One is an idle speed screw and the other is either a idle mixture screw, a low speed adj or high speed screw. Any thoughts appreciated.