[TNT]

Quote: Originally Posted by ds450power

hey tnt, this is the first time i've seen pics of the intake and exhaust ports, and to me those look huge compared to other 450 models i've seen. is it just me or are they really really big?

The whole DS intake track is designed to move some big air compared to the rest, big bore, throttle body, valves, and a fairly straight intake breathes easy. That has some advantages and disadvantages. Its complex, if you understand the venturi the larger mass of air can be manipulated, at the intake port for a pressure drop, more velocity by epoxy or coning them down. More velocity less pressure works in conjunction with intake vacuum to savage air to the intake stroke for better fuel atomization(combining of fuel-air molecules to one molecule), why with EFI the intake port are normally rough since this mix takes place at the manifold/port vs in a carb. Also, bigger flow of air allows for more advanced ignition timing at low rpm which is safer for the engine compared to say the 5 valve YAM design. More advanced timing at lower rpms is safer since there is less piston movement, lower engine loads, less cylinder charging and turbulence to not push the cylinder down as it is moving up with a large combustion force or chase the piston down the cylinder for max power and timing at TDC. The YAM requires just the opposite, timing close to TDC at low rpm more advanced at WOT.