Was going with the SE255 cams:
Road Master
Joined: Jan 2008
Posts: 853
Likes: 5
From: Mnpls MN
Fuel Moto did some dyno runs on his TC96 with the 6-6's and no other mods. His TQ peaked at 103 with HP at 92, while most 255 charts I've seen run in the same neighborhood for TQ and about 7-8hp less. The big difference is in the low-end. The 6-6 chart looks peakier, more like Pikes Peak, while the 255's start earlier and stay near the peak up to about 4500 rpm, a much flatter curve. Take a look at these two charts, but note that the graduations aren't the same, so the Fuel Moto chart (top) looks peakier against the 255's (bottom) than it really is. TQ is about the same except below 2500. The 255's retain the low-end much better at 2200 (90 vs. 80). So, you are making better power down low but sacrificing it at the top. Be advised that this dyno chart is the best I've seen on an otherwise-stock TC96 with 255's and most don't make these peak numbers. I would guess the 6-6 numbers are also near the best you might obtain since Fuel Moto is an accomplished tuning outfit.
I am anxious for Fuel Moto to test the 6-6's with the 4° advance gear, which is supposed to shift the TQ curve to the left about 300 RPM. That would put the low-end near that of the 255's, but peak-HP would certainly take a hit.
Which is right for any given rider depends on where you want the power. I'm a member of the gang who worships the low-end and midrange while placing little priority on peak-HP (moving the TQ curve up with no shift to the right), but others may prefer to sacrifice the low-end and gain more on the top-end (moving the curve up and to the right). The first group has much less to choose from, as when stock compression is retained it is difficult to hold onto the low-end TQ with longer duration and later intake close specs, and most performance cams tend to have these characteristics. The 255's are a very odd design that obviously emphasizes low-end and midrange TQ (~10% increase) but unapologetically offers little increase in peak-HP (maybe 5% increase). It also leaves little room to grow if someday you want to make a dyno shoot-out winner, as with its mild duration and early intake close it will likely never make more than 90hp even in a 103 with 10:1 compression.
I am anxious for Fuel Moto to test the 6-6's with the 4° advance gear, which is supposed to shift the TQ curve to the left about 300 RPM. That would put the low-end near that of the 255's, but peak-HP would certainly take a hit.
Which is right for any given rider depends on where you want the power. I'm a member of the gang who worships the low-end and midrange while placing little priority on peak-HP (moving the TQ curve up with no shift to the right), but others may prefer to sacrifice the low-end and gain more on the top-end (moving the curve up and to the right). The first group has much less to choose from, as when stock compression is retained it is difficult to hold onto the low-end TQ with longer duration and later intake close specs, and most performance cams tend to have these characteristics. The 255's are a very odd design that obviously emphasizes low-end and midrange TQ (~10% increase) but unapologetically offers little increase in peak-HP (maybe 5% increase). It also leaves little room to grow if someday you want to make a dyno shoot-out winner, as with its mild duration and early intake close it will likely never make more than 90hp even in a 103 with 10:1 compression.
This is a good post! Thanks
Extreme HDF Member
Joined: Sep 2005
Posts: 11,615
Likes: 50
From: Baton Rouge, LA
Below is a copy of the dyno run posted on Nightrider; under "TC95 Building A 100 HP . It's from a 100 HP engine built by CycleRama. I've pasted some dialog to show why peak torque is not important. The 255 cam is nice but the Woods TW6 is a bit nicer...No it's a lot nicer, IMO. $100 -$200 more is a drop in the pail compared to what you get with the TW6.
You can easily recover the low-end on 6-6's by simply installing higher-compression pistons, but that takes more money, and the thrust of my points were that the 255's were a good option for those on a low budget who want an increase in low-end and midrange TQ in an otherwise stock TC96 (with Stage 1 stuff). Many of us ride between 2000-4500rpm most of the time and want more power there.
Last edited by iclick; Jan 28, 2010 at 08:56 PM.
Extreme HDF Member
Joined: Sep 2005
Posts: 11,615
Likes: 50
From: Baton Rouge, LA
Thanks. I hope it helps. I should also mention that the Wood 6-6 with 4°-advance gear would also add at least $75 to the total price of the job. I did consider this option, but at $475-525 depending on where you buy the cams and gear that was above my cheap-*** budget. My cam job cost $285 including the bearing tool, and I could kick myself because I know I could've cut it down to $200! 
Road Master
Joined: Jan 2008
Posts: 853
Likes: 5
From: Mnpls MN
I'm a bit late and out of order with my replies. In the first place the engine used in the chart was a TC95, which is a different animal altogether. It also has flat-top pistons installed, which ups the CR over stock and explains the good low-end characteristics and flatter TQ curve. The cams used are CycleRama, with little info provided on their specs. This thread and my charts pertain to TC96's with stock compression, and when you add other engine mods like compression increases you are opening up a totally different kettle of fish, not to mention more expense. There are plenty of builds that will "smoke a 255," as in a drag race you're likely above 5k RPM during the race and 255's are clearly not in their element that high.
You can easily recover the low-end on 6-6's by simply installing higher-compression pistons, but that takes more money, and the thrust of my points were that the 255's were a good option for those on a low budget who want an increase in low-end and midrange TQ. Many of us ride between 2000-4500rpm most of the time and want more power there.
You can easily recover the low-end on 6-6's by simply installing higher-compression pistons, but that takes more money, and the thrust of my points were that the 255's were a good option for those on a low budget who want an increase in low-end and midrange TQ. Many of us ride between 2000-4500rpm most of the time and want more power there.
The other thing that you missed and you may have to go to NightRider to read it is; this enine is a low compression engine.
Another thing, Flat top pistons do not raise the compression. Compression ratios raise compression. Do you know anything about Physics?
I was showing the truth, but you can not see the truth because the truth is not with you.
that was a nice post you Quoted from Fuel Moto, inspite of the fact that you are poor salesman.
Road Master
Joined: Jan 2008
Posts: 853
Likes: 5
From: Mnpls MN
Another thing, that otherwise stock bike of yours has flat top pistons. Does that raise the compression ratio??
the only difference between the 96 and 95 is the stroke. Otherwise they are the same animal. A twin cam engine. You can dissect the heads but they are both twin cam engines.
Iclick, you don't know as much as you boast about. I am the producer!
the only difference between the 96 and 95 is the stroke. Otherwise they are the same animal. A twin cam engine. You can dissect the heads but they are both twin cam engines.
Iclick, you don't know as much as you boast about. I am the producer!
Extreme HDF Member
Joined: Sep 2005
Posts: 11,615
Likes: 50
From: Baton Rouge, LA
The other thing that you missed and you may have to go to NightRider to read it is; this enine is a low compression engine.
Another thing, Flat top pistons do not raise the compression. Compression ratios raise compression. Do you know anything about Physics?
I was showing the truth, but you can not see the truth because the truth is not with you. that was a nice post you Quoted from Fuel Moto, inspite of the fact that you are poor salesman.
Last edited by iclick; Jan 28, 2010 at 10:53 PM.
Extreme HDF Member
Joined: Sep 2005
Posts: 11,615
Likes: 50
From: Baton Rouge, LA
My bike has stock pistons which have a top surface that could be referred to as a "flat top." The "flat-top piston" typically referenced by HD and elsewhere is an aftermarket HD item that raises the compression ratio to 10:1 in a TC103 and 9.4-9.5:1 for the TC95 using stock heads. There is no such option for the TC96. It is a term used to differentiate it from the higher-compression domed pistons HD offers. Once again, reference the SE catalog if you need more info.
the only difference between the 96 and 95 is the stroke. Otherwise they are the same animal. A twin cam engine. You can dissect the heads but they are both twin cam engines.
TC95: Bore 3.875", stroke 4.0"
TC96: Bore 3.75", stroke 4.375"
TC103: Bore 3.875", stroke 4.375"
First, the TC96 has a longer stroke and a smaller bore than a TC95. Second, the TC88/95 is a totally different engine with few common parts compared to the newer TC96/103 design. Apples and oranges.
Iclick, you don't know as much as you boast about. I am the producer!
Cruiser
Joined: Dec 2008
Posts: 146
Likes: 0
From: Boise Idaho
ICick, that has to be one of the clasiest responses I have seen on this forum. Thanks for all the great info.
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Outstanding HDF Member
Joined: Oct 2007
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From: Yokohama
iclick, why not get your bike dynoed so we can see once and for all what kind of power is made by a Jackpot power package plus 255 cams?
It would be extremely useful info for those of us considering what cam to get.
It would be extremely useful info for those of us considering what cam to get.
Seasoned HDF Member
Joined: Aug 2009
Posts: 9,243
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From: west Michigan
Well, I suppose it's kind of late in the thread for this but a reputable local indy and a nearby dealer with a good reputation both recommend the S&S 510s. To me, the 510 looks a lot like the Andrews 37 with less exhaust duration. It has a nice lope at idle.
Last edited by RK4ME; Jan 29, 2010 at 02:34 AM.