Since this is what I call an inline engine {not a V} and the engine is a 4
stroke means both pistons come up at the same time. Almost impossible to
balance perfectly, the counter balance method would be the best for
drivability. That being said, you'll have to balance it as if it were a
single cylinder. Probably have to add a lot of weight to the counterweights
I am sure. Will make for a rough idle I am sure if you balance it for higher
RPMs. Will free up a little HP maybe.