- Joined
- Jun 30, 2012
- Messages
- 13,261
I really like the small Italian bikes in this video:
http://www.youtube.com/watch?v=g-I38mZmZNk#t=1079
http://www.youtube.com/watch?v=g-I38mZmZNk#t=1079
xbacksideslider said:Ducatis - Dr. Taglioni didn't know much about how to design an intake or exhaust port or combustion chamber.
Ports came in low and at right angles to the cylinder, always a bad idea. Hair pin valve springs were a dead end too. Must have been a design theme - keep the head short in height.
The rest of the engine's design was just fine, even great. Simple functional beauty and well executed.
The chassis too, superior yet minimal.
Same head/ports on all of em. The 250s could breath, the 350s could be made to breath . . . . sort of, short rod narrow cases for the 350s. Good fuel important too. The 450s made OK dirt bikes because they could only breath at lower engine speeds, so cam and compression optimized for that.
xbacksideslider said:Ducatis - Dr. Taglioni didn't know much about how to design an intake or exhaust port or combustion chamber.
Ports came in low and at right angles to the cylinder, always a bad idea. Hair pin valve springs were a dead end too. Must have been a design theme - keep the head short in height.
The rest of the engine's design was just fine, even great. Simple functional beauty and well executed.
The chassis too, superior yet minimal.
Same head/ports on all of em. The 250s could breath, the 350s could be made to breath . . . . sort of, short rod narrow cases for the 350s. Good fuel important too. The 450s made OK dirt bikes because they could only breath at lower engine speeds, so cam and compression optimized for that.
xbacksideslider said:And, yes, regarding the L twins, the ports/combustion chamber are similarly flat in entry/exit and the same thing happens, the 750, as two 375s runs well - at that displacement, they heads are at about the limit of what they can flow to run out to the RPM limits of the pistons/rods and so on. When they pushed the displacement up to 900cc it became a torque monster unable to spin out absent radical cams, which the desmo system, with its potential for very sharp opening and closing ramps can/does deliver.