Big Bore Kit Triumph. New. 650cc - 750cc. 9 stud, 76 mm bore = 750 cc. 650 cc 9stud head can be used. Compr. 8,6:1. ROUTT Big Bore. E6304+100cc = 70-6304, 750cc. barrel, pistons, head gasket PS214. Cylinder and rings made in England. Please look at all pictures.