I have run very simular tests with glow driver and volt meter attached with a 25cc Homelite engine on glow/gas. With no mufler attached...idle was about non-existant. The engine needed a muffler to hold some heat in for idle. If I turned glow driver up...its fine on idle. With muffler idle was only fair....and engine would quit without golw driver help. I did take some tinfoil and wrap top fins so engine would run a little warmer at idle. That helped a lot. I am going to place cylinder in my Lathe and reduce fin area on top fins near glow plug. I did that first on a scrap cyl...its easy. So I got to do a runable one next. Capt,n Added cut down cylinder