Exhaust crossover pipe

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Nov 7, 2008 | 05:34 AM

#11

Roadjunkie1

Banned

Joined: Feb 2008

Posts: 1,943

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From: Chicago.

Quote:

Originally Posted by themensh

I put on a FULLSAC true dual kit....which eliminates the crossover.
I noticed no lack of power or torque. The bike was still hot enough
that my girlfriend would put her leg on top of mine at stop lights though.
Looks good.....runs good.......but was still hot.
Luckily I bought it from a member here, and at a decent price.

Chuck

Did the same thing and am very pleased. Also switched to a colder plug and better air filter. The engine sounds great, runs cooler, breathes easier and noticed no loss of power.

Am very satisfied with the true dual set up. (Fulsak)

Nov 7, 2008 | 05:39 AM

#12

IlDuce

Road Warrior

Joined: Jul 2008

Posts: 1,274

Likes: 9

From: Tampa, FL

I always thought cross over pipe was to distribute the heat equally, am i wrong?

Nov 7, 2008 | 05:44 AM

#13

mduggan

Cruiser

Joined: May 2008

Posts: 161

Likes: 0

From: Middleburg, FL

When I did the exhaust system on my 4WD, I was told that the crossover pipe (called a balance pipe by some) balances the flow of exhaust gases between the two pipes that feed it. This helps keep the exhaust speed and back-pressure even on both sides of the engine. It is especially important when the exhaust system is not of equal length on both sides. Look at your true duals and you see a lot of pipe curving around the rear cylinder. This is done to give the left and right pipe identical volume and distance for the exhaust gasses to travel. On an all-into-one system, this is managed internally (in the single pipe). Most things that I read lead me to believe that the all-into-one systems are the most efficient systems and make the most power. If you could straighten a set of duals, you should have two basically identical pipes. I would imagine that if you eliminated the crossover pipe on a stock system and didn't correct for volume and length, you could potentially lose some performance or exhaust efficiency. You may not feel the difference in the seat of your pants, but the engine will probably not run as efficiently as it should.

Nov 7, 2008 | 06:43 AM

#14

Ridewva

Grand HDF Member

Joined: Oct 2004

Posts: 3,842

Likes: 502

From: Northern WV

Quote:

Originally Posted by mduggan

I would imagine that if you eliminated the crossover pipe on a stock system and didn't correct for volume and length, you could potentially lose some performance or exhaust efficiency. You may not feel the difference in the seat of your pants, but the engine will probably not run as efficiently as it should.

Even if you would make them even, being separate they can't scavenge. 2 into 2 (w/o a crossover) is a performance downgrade. If the crossover is located where it heats your leg, eliminating it will eliminate that source of heat but at the expense of performance. A better solution would be to relocate the crossover (like was done this year) or probably even better, a 2 into 1.

Nov 7, 2008 | 07:11 AM

#15

ken thompson

The Schlong Man

Joined: Mar 2007

Posts: 3,772

Likes: 4

From: Nantucket

True duals look better and sound better to some. People also claim that is removes some of the heat from their right leg. Personally I don't like gaping hole it leaves between the rear of the motor and frame. Performance wise the closer you can get to a 2 into 1 set-up the better performance, which the stock pipe is. True duals are in fact a step backward in performance on a bike like a touring HD.

Nov 7, 2008 | 10:45 PM

#16

ezriderpgh

Thread Starter

Stellar HDF Member

Joined: Feb 2008

Posts: 2,156

Likes: 1

From: Pittsburgh, PA

Quote:

Originally Posted by Ridewva

It is my understanding that the crossover has been virtually eliminated on the '09, the front cylinder runs back on right and then under and out the left rear while the rear cylinder goes out the right, they mingle a tiny bit but are really seperated by design, which puts all the heat on the right side and from talking to owners of '09 tour bikes they are not pleased with it at all.

Last edited by ezriderpgh; Nov 8, 2008 at 01:08 PM.

Feb 8, 2012 | 09:09 PM

#17

drspencer

Road Warrior

Joined: Feb 2010

Posts: 1,534

Likes: 10

I have a 2007 Softail Custom.

When removing the rear muffler today, I noticed that where the rear head pipe and the crossover attach together is very loose, like they're just slipped on together.

Is this the correct fitment, or do I need to start fixin'?

Thanks

Feb 8, 2012 | 10:28 PM

#18

DDuess

Road Captain

Joined: Sep 2008

Posts: 727

Likes: 1

From: Silverdale, WA

Harleys have relatively small mufflers compared to their displacement. Small mufflers have to be able to be quiet the exhaust, this can be restrictive and limit power. A crossover pipe allows the exhaust gasses from one cylinder to flow through both mufflers, thus reducing the restriction.
Crossover pipes can improve mid-rpm torque if properly located, Triumph apparently discovered this in 1964. Originally the idea was to increase the airflow through the small mufflers on the american spec'd bikes. They noted that the crossover added performance in the mid-rpm range. (I read about this in Rider magazine)