Destroke can be a really good solution for Bonneville. Speed of sound is lower, in thinner air, and I gained higher useable RPM without hitting the 0.5 Mach wall (port speed). I also needed the room for bigger valves and seats (we also had to raise the intake ports).
My destroke CX650 engine was always faster than the stock stroke "bigger" engine Both my engines used larger than stock bore (to allow a ring pack for modified Hayabusa). The 680cc engine never ran past 159, but the destroke version ran 164 (all with same gearing, cam, carbs, etc.) The shorter stroke engine did not wet down my left knee with gasoline mist at 10-11,000 rpm. The stock stroke engine made strange intake sound and had spooky little clouds hanging out of the velocity stacks. It really hit a wall at 159 and change.
The downside of destroke was the expense....I had to take Castillo extra crankshafts, pay the price for each destroke, and accept loss of two cranks that cracked excessively during the final work. That was perfectly fair, as they had to do all the hours of work regardless of how it came out. It was strictly luck of the draw, and no fault of theirs....they did what was really difficult when no one else would even try.
Sometimes what seems obvious has a hidden surprise....especially when bigger does not prove to be better. Thanks fellows, for letting me ramble through some old memories. The years have sure slipped away, here, and my hobby these days is relearning how to use the right side of my body after the stroke last November. The good news is I can still ride my e-bicycle ok!
