I am supprized you have not got more help by now. If a wabro carb would bolt on...that may help if you can get one off another one of your engines. If I get time ...I will read up on the Tartan twin and see. You may also consider spark ignition and eliminate the glo plugs. Make sure both cylinders have about the same compression and the crankcase sals are good. Hope this helps for now. Capt,n