true duals
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Tourer
Joined: Dec 2009
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From: New Kensington, PA
true duals
What would changing the true duals back to standard equipment pipes with the rinehart muffs and quiet baffles do to a cam job? Compression ratio go up? How much? Move rpms lower? Similar to putting in a 4* advance timing gear?
Road Warrior
Joined: Mar 2007
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From:
What you're suggesting doing should improve your low end torque. If your bike is a bagger that is a good thing. Baggers are heavy and torque is your friend.
Club Member
Joined: Jun 2007
Posts: 45,429
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From: Bedford UK
I had true duals on my S&S 107. S&S approve of that as a workable setup and I ran it for 3 years and was very happy with the performance, which was as predicted by S&S. I have just replaced the exhaust with a 2-into-1 and once again had the bike set-up by my S&S specialist. Torque is slightly increased, but especially in the range up to 3,500rpm, where it really counts.
The stock pipes also give good torque, which is why Harley uses them, so they may give slightly improved performance, just as my new pipes have. You will get the most out of any change of set-up by having it optimised by a competent tuner.
The stock pipes also give good torque, which is why Harley uses them, so they may give slightly improved performance, just as my new pipes have. You will get the most out of any change of set-up by having it optimised by a competent tuner.
Elite HDF Member
Joined: Jun 2007
Posts: 3,873
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From: NW Arkansas
Took my tru-duals off and went back to stock header with 4" Jackpots, looking for more torque. It worked! I also added SE255s and a 68 tooth rear sprocket, so it is not a pure comparison. (08 UC)
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Tourer
Joined: Dec 2009
Posts: 472
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From: New Kensington, PA
I was thinking about putting in the se 204's but wanted the power to start a little sooner. I looked at the 255's but, was concerned about hard starting and I think the 254's might be a little bit milder than the 204's. Not sure though since I haven't seen a dyno sheet for them. The dealer I talked with and this forum said a 4* advance gear is a bad idea for the 204's. A calculator I found online said the static compression ratio would be 9.56:1 with the 204's. I thought the exhaust would have some effect on the power band like the 4* advance gear. But if it doesn't do anything else, it may not get me where I want to be. I think the 204's might have been made for the older intake/exhaust manifold which was not as good at allowing air to move as the newer ones for the tc engines. In other words, I think the 204's will keep the exhaust valve open a little too long and pull too much air from the cylinder lowering the compression and therefore not providing as much torque as they are capable of. Seems like the intake/exhaust overlap is too long. I think? Anyway, I'm not sure what I want to do yet but am trying really hard to learn as much as I can since I have to save to do this. I want the best setup I can for low to midrange torque that comes on smooth around 2000rpms and will extend to about 5000 rpms. My '08 Road King seems a little sluggish. Probably because of the weight and the gearing in the transmission?
Last edited by pilgrim08; May 9, 2011 at 08:07 AM.
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