Reader Yash comments that singles require a “heavy flywheel to improve tractability [and] eliminate rough idle.
“…it takes a heavy toll on acceleration and top speed.”
Yash is right that these are serious concerns, but there are many thousands of successful modern singles—four-stroke MX engines are prime examples. And, yes, it’s possible to provide too little flywheel, as was the case in the first year of Supermono racing, when big singles so often stalled in slow corners—sometimes to the point of being comical. Since then the sophistication of ECU programming has corrected this situation.
As to the “heavy toll on acceleration,” Yash is right again. When the late C.R. Axtell tested the Cosworth Norton on his dyno, he said it was “the slowest-accelerating engine I’ve seen.” It was a parallel twin (both pistons moving together) with both a massive central crank flywheel and a pair of hefty primary balancer shafts carrying eccentric weights.
In the case of Ducati’s Superquadro single, you’ll notice that the amount of flywheel mass on the crankshaft itself is quite limited. The designer has taken care to make crank and…
