What difference does it make if a V-twin has a 70 degree as opposed to a 45 degree angle?

Question

A lot of cruisers' specs include the angle of their V-twin motors. So I was wondering what that has to deal with? Thanks!

Answer 1

the angle effects vibration. 45 degrees with a common crankpin makes for lots of vibration.

Answer 2

it has to do with the cumbustion of the engine (efficiency of burning fuel & air). this will contribute to a smoother running engine.

Answer 3

The loping sound common among Harley engines is due, among other things, to the pattern of firing the cylinders.  The front cylinder fires first, then the engine rotates 315 degrees and fires the rear cylinder.  Then the engine has to rotate 405 degrees before it fires the front cylinder again.

When you've got a 70 degree engine, the rotation between the front cylinder firing and the rear cylinder firing is 290 degrees and an additional 430 degrees to fire the front cylinder again.

The advantage of the 70 degree engine is a smoother powerband, the advantage of the 45 degree engine is the loping "potato-potato" sound it makes.

Answer 4

It won't matter much. It might sound a little different.

Answer 5

90 degree engines tend to be fairly smooth because of the tendency for primary imbalances to cancel out secondary imbalances.  The farther you get away from the 90 degrees, the more vibration.  That said, on the 80's v twin Honda Ascot (I think it was), Honda used a staggered crankshaft so that even though the cylinders were considerabaly less than 90 degrees apart, the crankshaft throws were 90 degrees, which made for a smoother engine.

Answer 6

It has to do with smooth the motor runs. Changing the angle smooths the motor out.