Reason Why Rear Header Wraps Forward? - 1130cc.com: The #1 Harley Davidson V-Rod Forum
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Old 11-22-2012, 10:37 AM   #1
pgilliam1
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Reason Why Rear Header Wraps Forward?

Is there a reason why the rear header pipe comes forward? The pipe comes close to my leg and I can feel the heat and it burns my rain suit pants that fit kind of loose. Bub Jug headers don't do this, they just go straight back (but they are different lengths). Seems like most of the other aftermarket headers come forward too.
I suppose it adds to low end torque or something of that nature, but does it make that much of a difference? I'm considering the Bub's so I' need to know.
TIA
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Old 11-22-2012, 11:09 AM   #2
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My guess is: To avoid a significant torque split between the two cylinders, the headers should be the same or similar in length.
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Old 11-22-2012, 11:16 AM   #3
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Old 11-22-2012, 11:20 AM   #4
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Headers on cars are usually designed to specific lengths not only to let the air out faster, but smoother. I'm not sure how much of it translates to bikes, but they're designed to meet together at specific distances so the "pulse" of one cylinder actually helps to pull the air from the opposing cylinder(s).
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Old 11-23-2012, 10:21 AM   #5
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You will see a power loss with the bub jug huggers. The reason others wrap around the cylinder is as already stated. The reason they don't fit more tightly around the cylinder and give more leg clearance is cost. My rear pipe is only 5/8" from the cylinder. It clears my leg so well that I need no heat shield, but was not an easy thing to accomplish.
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Old 11-23-2012, 12:27 PM   #6
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Quote:
Originally Posted by mikeinatlanta View Post
My rear pipe is only 5/8" from the cylinder. It clears my leg so well that I need no heat shield, but was not an easy thing to accomplish.
So how did you accomplish this? Any pics? And wouldn't locating the pipe closer to the engine cause problems with spot heat transfers?
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Old 11-23-2012, 08:09 PM   #7
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I'm still 5/8" away from the jug so no heat issues at all. The issue is that the compound bends can't be done with a bender and must use prebent mandrel tubes welded together. Next issue is that the pipe must then curve out to clear the water pump.
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Old 11-24-2012, 11:52 AM   #8
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Very nice - THX for the pic. When I first rode the V-Rod the heat from the pipe was the only issue I had. I decided I could live with it, but I didn't count on the burns on the pants and marks on the pipes.
Harley - are you paying attention???
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Old 11-25-2012, 11:39 AM   #9
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If the heat is an issue,why not wrap it with header wrap?.
Many riders wrap their tubes to control heat and allow for more comfort while riding.
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Old 11-25-2012, 12:22 PM   #10
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Quote:
Originally Posted by Thundering6 View Post
If the heat is an issue,why not wrap it with header wrap?.
Many riders wrap their tubes to control heat and allow for more comfort while riding.
I guess it's a matter of taste. I usually prefer performance over looks, but in this case I think the header wrap makes a great looking machine look like a rat bike. Not that there's anything wrong with rat bikes, but the V-Rod is not one that I'd rat out. IMO.
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Old 11-25-2012, 12:25 PM   #11
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Isn't it possible to wrap it and then fit the heat shield over it?
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Old 11-25-2012, 12:26 PM   #12
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Quote:
Originally Posted by pScyko View Post
Isn't it possible to wrap it and then fit the heat shield over it?
There's an idea. I'll look into that.
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Old 11-26-2012, 10:31 AM   #13
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I suspect it originally was a styling statement like most of the rest of the V-Rod features. Other than that there's no reason for it to be so different in length.
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Old 11-26-2012, 10:48 AM   #14
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I stole this from another thread.

1) Cam timing IS the same between the front and rear heads yet different from intake to exhaust.
2) Velocity stack height IS different due to different length exhaust pipes.
3) The intake port length in the castings front and rear are the same.
4) The o'ring @ the velocity stack is to keep fasteners in place during assembly/diassembly so they don't fall into the intake ports.
5) The K&N air filter is less restrictive than the SE one.
6) Cutting the velocity stack heights to be even in length will effect the performance of the powertrain due to the fact that they mimic exhaust header length, but I do not know how.
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Old 11-26-2012, 11:15 AM   #15
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Quote:
Originally Posted by VrodG View Post
I stole this from another thread.

1) Cam timing IS the same between the front and rear heads yet different from intake to exhaust.
2) Velocity stack height IS different due to different length exhaust pipes.
3) The intake port length in the castings front and rear are the same.
4) The o'ring @ the velocity stack is to keep fasteners in place during assembly/diassembly so they don't fall into the intake ports.
5) The K&N air filter is less restrictive than the SE one.
6) Cutting the velocity stack heights to be even in length will effect the performance of the powertrain due to the fact that they mimic exhaust header length, but I do not know how.
All good info but the rear exhaust pipe is about 16 inches longer than the front and the difference in the velocity stacks can't be over at most 4 inches (best guess on stacks - I didn't measure). The more I learn about the mechanics of exhaust sytems, the more I have to lean toward dyno results that conclude that the 2-into-1 systems produce the most power (on non FI engines) regaurdless of how they're routed. I remain confused.
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