wrote:
Bertie the Bunyip wrote:

...
What th ewirter seems to be describing is an arrangement where two

opposing

pistons share a crankpin. I've seen twins like this and they vibrate

like

hell. A boxer (whihc most all flat opposed engines are) is a much

smoother

arrangement.



What is the distinguishing characteristic of a boxer, that opposing
cylinders fire simultaneously?


I think the main feature is that the cylinders go in and out in
opposition thus giving very good primary balance. You always have the
torsional vibration from firing and there is also secondary imbalance.

Matt