[EmyJ]

im sorda confused as to what this means....i know it means there are 2 chambers and they either run up or down or both up and both down. but what makes this difference than other engines? and do all 250's have it?

 

[Freakinout]

I'm not sure what you are asking, but on a twin cylinder motor while one piston is 'up' the other one is 'down'.

 

[OmahaRider]

Think of it as an inline 4cyl with 2 cylinders shaved off-------different than a V-twin or opposed twin(pancake)

 

[jonesie619]

parallel as in side-by-side, as opposed to a v-twin.