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Hi fellow bikers, After just completing the install of true dual exhaust on my 07 Road King, I was wondering why HD continues to manufacture V twin cruisers with the crossover pipe? Anyone know of the reason? And if the bike was flashed after installing slip-ons, would it have to be flashed again for the duals.
Thanks
 

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By flashed I'm assuming that you mean a stge 1 download and generally that is all preset with no adjustables. You probably need a race tuner, fuel pack, or some type of adjusable fuel management to get full benefit from you're mods. The best deal would be to have it tuned on a dyno.
 

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The xover pipe improves exhaust scavenging. the best performance on the harley v-twin comes from a 2-1 pipe while a 2-2 may look and sound cool you will lose some performance most noted in low end torque. You probably had your ecm flashed to a stage one by the dealer.If you still have a stock a/c you might be ok if not you may need some type of fuel mgmt device.
 

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The stock head pipes give you more low end and mid range compared to the true duals with which you will gain some on the top end but lose down low.

The D&D fat cat 2 into 1 seems to be an excellent alternative to the factory system. It has enough flow that you don't lose anything anywhere and takes advantage of the scavenging advantage of a 2 into 1.

I don't see any advantage to true duals on a heavy touring bike that is not operated continuously at the upper end of the powerband. These are not high rpm engines. The factory system acts as a 2 into 1 at low to mid rpms then when you open the throttle up wide open and pressure begins to build in the right muffler it diverts excess pressure through the left muffler operating as a 2 into 2 system. The best of both worlds.
 

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Monty, the stock system is a really poor performer (as in pi$$ poor). It scavenges little and construction is poorly executed. I've seen some head pipes (front and rear) partially obstructed by the cross-over, not a good thing.
As mentioned, a 2-1 makes the most gain followed closely by a 2-2. You'll notice very little difference between a 2-1/2-2 on a basically stock motor. The difference will be more pronounced on medium to highly modified motors.
 

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There are several other reasons for running true duels. 1: Looks, 2: Sound, 3:Cooler by eliminating crossover pipe (older models), 4:Eliminating Catylitic converter (newer models)
5: Higher speed roll-ons are awesome. Dyno charts show a dip in torque at lower speeds, but I sure don't notice it, and it more than justifies it with the increase in highway passing power. JMO
 

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I switched to true duals mainly to get rid of the stock cross-over pipe because of the heat. I did have a SE super tuner and dyno accomplished. I get a very small dip in torque at about 2200 to 2350 rpm or so. At least that is what the dyno sheet I have posted in the dyno forum said.

I've been told that a high performance air cleaner effects the ECM tune more than the addition of slip on mufflers. Going to true duals probably leans out the tune more than just slip ons.

If your bike was mine I'd do more than just have the ECM flashed. The alternative is much more expensive but you'll be pleased with the outcome, I believe. There are a number of ECM tuner's you could go with. Do some research and pick the one you feel will work best for your application.
 

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I have never noticed a heat issue with the stock head pipes and my girlfriend has never complained. I have an 05 Electra Glide with the stock head pipes, 11 Ultra Classic stock mufflers and a K&N air filter. Bike runs great and gets 45mpg. I don't miss the 96 and 6 speed that was in my 07 Super Glide.
 

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I went with true duals when my stock headers cracked at the crossover joint. I've used them with both Hi-flo and stock mufflers and don't really notice much power difference from the crossover setup. Of course, that's just my ass dyno talking.

What I do get is the heat advantage. No more fried thighs in stop/go traffic. That's a higher value bonus for me than a small power gain/loss. Of course, if I had one of the newer models with the crossover underneath the motor, I'd probably not mess with it unless it cracked again.
 

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Monty, the stock system is a really poor performer (as in pi$$ poor). It scavenges little and construction is poorly executed. I've seen some head pipes (front and rear) partially obstructed by the cross-over, not a good thing.
As mentioned, a 2-1 makes the most gain followed closely by a 2-2. You'll notice very little difference between a 2-1/2-2 on a basically stock motor. The difference will be more pronounced on medium to highly modified motors.
Where did you get the data that says the stock pipe doesn't perform? I find it hard to believe that a true duak set up will outperform the stcok header. I've run them both and the stock pipe outperforms the duals any time and day. Just curious where you got the data that shows the stock pipe is as bad as you say.
 

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I made so many changes at once it is hard to tell which one helped the most. I went with Khrome Werks headers in the 09-10 style because of the way the pipes snake around and keep the heat off of the passengers legs and feet (gotta keep mama happy). They have a crossover welded in between the pipes like the V&H power chamber has - they said they got more performance WITH the crossover. This combined with the Andrews 26 cams, V&H VO2 air cleaner system, and Kury Crusher mufflers tuned with the TTS has made this bike an amazing pulling machine. I bumped the rev limiter to 6200 and contrary to what many have said, this thing pulls HARD up to 6 grand, and I believe the headers are part of the reason for this. The cam is supposed to fall off at 4800 rpm, but I believe the pipes add to the upper end continuing to over that. I did tons of research (ask my wife!) before I decided on he components I bought, and it really paid off.
 

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Hey Trumpeter, here it is 2015. I have the same problem with the rear header pipe cracked at the 90 degree mark. I like the looks of my 2 into 2 over the top, and it performs well. But I'm leary of repeating the same issue, if I just replace the 90 small piece?
 

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Hey Trumpeter, here it is 2015. I have the same problem with the rear header pipe cracked at the 90 degree mark. I like the looks of my 2 into 2 over the top, and it performs well. But I'm leary of repeating the same issue, if I just replace the 90 small piece?
Well, I've put about 30K miles on my bike since that post. This season, the rear header of the V&H duals developed a leak... Inspection reveals that it rusted out. I've done a lot of riding in severe weather for long distances, so my ride takes more of a beating than most. I had it welded as a temp fix while I wait for a replacement. Staying with the dual setup though.
 

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Just wondering,I have a 06 Electra Glide, I have done the intake, and installed slip ons. I am getting the local shop to instal a Harley tuner and putting it on the dyno to get it dialed in. What I am wondering is, should I put true duals on before I get tuner and dyno?
 

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Can I ask why? The service guys at the Harley shop are telling me that it’s good ??? But I know nothing about what tuner to get. All I really want is for bike to run good, with maybe some extra fuel mileage. I only have 4500 miles on a new Harley long block engine.
 

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what therm said,,, harley tuner is a glorified ecm flash...
I believe it is always advisable to do all the mods at once then tune it,, saves a fortune in tuning costs..
 
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