My son has a big Harley. I notice the front cylinder exhaust Ys as it comes out and goes to both tailpipes. The back cylinder exhaust only goes to one tailpipe. What is the reason for this? Just curious.

 

I think you mean the rear cylinder Y's and goes to two pipes and the front goes only to one, correct? Harley makes the exhausts with the crossover pipe that scavenges the exhaust. The majority of the exhaust goes to the one on the right. If you go with a complete 2 into 1 exhaust where both go into one muffler, it would make better power. You can also have each one go into its separate muffler, this is called true duals. They even out the exhaust and make it louder, but is not as powerful as the 2 into 1 or the stock crossover setup.

 

Thanks. Good answer.

I wasn't clear about "front" and "rear" cylinders. But, you nailed it for me.