Why do some high-performance motorcycle engines use a 270-degree crankshaft configuration instead of a 360-degree configuration in parallel-twin layouts?

1. To reduce the manufacturing cost of casting the crankshaft
2. To eliminate the need for any primary or secondary balancer shafts
3. To mimic the power delivery and exhaust note of a 90-degree V-twin while maintaining a compact layout
4. To allow the use of a single carburetor to feed both cylinders simultaneously