Oldnwiser
XS650 Enthusiast
I was studying a cylinder head from a 447 that I had as a spare . That was a long time ago. If I had a 533 case and 880 block and even a 447 head has enough room to fit a divider in and widen the port large enough for 2 stock size valves in each cylinder and put a larger exhaust valve in the front of each cylinder to the pipes . The engine is so strong that you could use two stock rockers per cylinder with one driven by the cam and the 2nd pinned to a rocker shaft on each cylinder with a carb for each cylinder. The exhaust being a single valve would make the bike appear stock. You could have the divider between the valves and up until the port feeding them would be round and the divider shaped into a vane and the port at the intake manifold could be oval and then round for a 40-42 mm carb for each cylinder would feed the two valves on each. If the cylinder is 87 mm I’d think that two intake valves per cylinder would feed well but possibly have a cooling effect by discharging cool air into the chamber. This is an idea to study, I really wish I were able to play with such things. Even a 750 cc 447 on Cafe, Bobber, Brat that has room for it would be neat. Get it to 70 ft lbs 70 hp on a 360 twin or a 270/90 that would sound like a car ripping around. It would be fun. Is it a a stupid idea? Believe me I built a straight axle 12.5:1 65 Mustang with a 289 4 speed in high school and I couldn’t get a race. It idled at 1500 and revved to 8000 with fenderwell headers. The front end came from a 63 Datsun 1 ton with a straight axle and torsion bars with Rack and Pinion from the truck . I rebuilt it and with a 4.56 9 inch rear locker and that banshee wailing 289 Even an LS6 Chevelle said No Thanks, while it was idling like a fueler, maybe the Tunnel Ram with the 850 DP was a warning Lol.