Crossover pipe...
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Cruiser
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Crossover pipe...
Does anyone know what purpose the crossover pipe serves on the tourers? I know a lot of people are running true duals these days, and those eliminate it...but I'm just curious what it's for.
Elite HDF Member
Joined: Jun 2006
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From: Longview, Washington
RE: Crossover pipe...
I've been told that it improves the exhaust scavenging. Someone else can probably describe it better than I.
I removed the crossover and installed a conversion kit made by Torres Cycles. I did it mostly to get rid of the hot pipe next to my leg. Also, I now have a "stereo" exhaust with the same sound on both sides. The stock system puts most of the exhaust out of the RH pipe. Check for yourslef. You can hold your hand over the left pipe easily but not on the RH side.
Guys say the true duals effects the torque. I didn't notice a change. With the Stage 1, I gained a bunch of power anyway.
Steve
I removed the crossover and installed a conversion kit made by Torres Cycles. I did it mostly to get rid of the hot pipe next to my leg. Also, I now have a "stereo" exhaust with the same sound on both sides. The stock system puts most of the exhaust out of the RH pipe. Check for yourslef. You can hold your hand over the left pipe easily but not on the RH side.
Guys say the true duals effects the torque. I didn't notice a change. With the Stage 1, I gained a bunch of power anyway.
Steve
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Cruiser
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RE: Crossover pipe...
A friend of mine told me about the "more exhaust out of the right muffler", and it suprised me when I put my hand down there and felt it. I've also heard a lot of guys say they've lost torque from the true duals...if you ask me, torque is more important than HP, especially on a touring machine. My buddies run 2:1 Thunderheaders on their dressers. I know that 2:1 is best for making torque, but the 2 bags/1 pipe look still hasn't grown on me...doubt it ever will.
Outstanding HDF Member
Joined: Jul 2007
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From: Indy area
RE: Crossover pipe...
ORIGINAL: bigbean78
Does anyone know what purpose the crossover pipe serves on the tourers? I know a lot of people are running true duals these days, and those eliminate it...but I'm just curious what it's for.
Does anyone know what purpose the crossover pipe serves on the tourers? I know a lot of people are running true duals these days, and those eliminate it...but I'm just curious what it's for.
It's not really a crossover, but the system isn't really a 2-into-1, either. The thing is, with a completely separate exhaust system for each cylinder, the bottom-end torque really does suffer in comparison to that produced elsewhere in the operating range. Just look at a bunch of dyno charts and you'll see that the torque curve is depressed in the lower ranges with them. Granted, when done right there will still be more torque there than there was with the stock system, but there's less added there than elsewhere. The best torque curves are high and flat, like can be best attained with a 2-into-1 system. They aren't necessarily the best for a "wow" factor as you accelerate but they make it so you don't have to be so picky about what gear you're in when you do.
I'm really interested in the new Bub 7 dual exhaust which is available with a "true" crossover tube. The crossover balances the system, (usually) making the lower-end torque better but doing that takes it in trade from the upper rev ranges (where the separate exhausts do have benefit). The stock H-Ds with all the plumbing on one side are essentially dual exhausts with a crossover.
Club Member
Joined: Jun 2007
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From: Bedford UK
RE: Crossover pipe...
ORIGINAL: bigbean78
I've also heard a lot of guys say they've lost torque from the true duals...if you ask me, torque is more important than HP, especially on a touring machine.
I've also heard a lot of guys say they've lost torque from the true duals...if you ask me, torque is more important than HP, especially on a touring machine.
Road Warrior
Joined: Sep 2007
Posts: 1,827
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From: Iowa
RE: Crossover pipe...
The "crossover" pipe equalizes back pressure between the cylinders. I believe with equal back pressure between the two cylinders makes tuning of the engine better/easier with one carb, I think...make sense? I was going to cut my "crossover" pipe off or use a conversion but it will make a 90 degree angle not good for flow. I elected to cut the left pipe instead. Keeps the flow smooth, creates a 2-1 for fee and drop some wait while I am at it : )
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RE: Crossover pipe...
I was one that took off my stock system too.
We recently did some experiments with different size baffles on each side with the stock system.
We actually got better torque and HP with 1 3/4 on the left and 2 1/4 on the right.
I'll keep my duals on just cause I like the sound. but it's interesting to see these numbers.
We recently did some experiments with different size baffles on each side with the stock system.
We actually got better torque and HP with 1 3/4 on the left and 2 1/4 on the right.
I'll keep my duals on just cause I like the sound. but it's interesting to see these numbers.
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Cruiser
Joined: Dec 2006
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RE: Crossover pipe...
ORIGINAL: grbrown
I have just fitted true duals to my Glide - as I write it is with my local expert who is fine tuning it. He tells me they only work well with plenty of back-pressure, otherwise they do indeed lose torque. [sm=confused06.gif]So some mufflers will work better with them than others. I have Harley fishtails (not SE ones) on my bike, which he reckons should be OK. I wait with bated breath! [sm=smiley26.gif]
ORIGINAL: bigbean78
I've also heard a lot of guys say they've lost torque from the true duals...if you ask me, torque is more important than HP, especially on a touring machine.
I've also heard a lot of guys say they've lost torque from the true duals...if you ask me, torque is more important than HP, especially on a touring machine.
I survived my go-fast days somewhat intact[sm=outcold.gif] and now ride for different reasons. I'm OK with all this but was surprised at the difference.
BG
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