Think about this in relation to siamese intake ports. As no. 1 piston is on the intake stroke the cylinder is filling with the intake charge. Due to the crankshaft design of 120 degrees between throws the ajoining cyl, no.2 intake vale breaks off its seat and the no.1 cyl stops filling. The cure, have the crank throws come up together and change the firing order, buy a 12 port head, or divide the intake port. Each has its drawback. I had this discussion with nonother than Bruce Crower many years ago. Ed Farrell
