Please advise I am a novice flyer will little expirience I purchased allot of items 2nd hand to enable me to start the sport and I have acquired a few OS four stroke engines. All the engines have been stripped and rebuilt and I currently use one in my trainer a 70, however on another plane I have the 91 surpass and although it runs it will not idle at low rpm with out the glow booster attached it uses a os F glow plug and I am running on four stroke fuel from a local hobby store. Again please help.