Sweet GP246F
New member
Does anyone have a 135 main jet for a 1974 - 1975 GP246F? The original Yamaha part number is 849-141432700. I have the head milled .015, cylinder bored .020, .002" thick head gasket, and ported/polished. Does anyone know if taking off a total of .081" for compression will require 110 octane? I am at .063 now, and have .018 to go by replacing the base gasket with my .002" gasket material. 
