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[Tom149]

I have been asked why I chose a 107CI build on my 06' FLHTCUSE (103CI) using TC 88 heads instead of my SE 103 stock heads, and why I didn't change out my exhaust (from TD's to 2:1) instead of increasing my displacement to 107CI. Here is my reasoning:

1. Quite a few reputable head porters recommend TC 88 or 96 heads over CVO 103 stock heads for porting and polishing as a result of the size and shape of the combustion chamber on the CVO 103 heads (too big & hemi shaped) and the huge valves that they incorporate. The roughly 85cc, bathtub shaped, TC 88 head will provide more efficient combustion and higher compression than the 95cc - 98cc SE 103 stock hemi-shaped head. I needed 10.1 - 10.2:1 compression to run the Andrews 54N cams efficiently and was able to get that in part by cc'ing the TC 88 heads to 87cc. To get 87cc's out of SE 103 stock heads would require welding up and CNC cutting the combustion chambers and/or severely milling them. I believe that Don Dorfman (Dewey's Heads) and Scott (Hillside Cycles) prefer the TC 88 heads for performance builds and some head porters I contacted would not even work on the CVO 103 heads.

2. While the heads were off, it was relatively easy and inexpensive (about $450.00) to bore my existing jugs and add the oversize (3.938") cp pistons increasing my displacement to 107CI. $450.00 is considerably less than a D&D Fatcat 2 into 1 exhaust system. Also, displacement = power and "there is no replacement for displacement", to coin a phrase. The 96CI or 103CI to 107CI conversion is a very popular build and almost all of the Independent Performance Shops are recommending/offering it. As long as you have a 4.375" stroker, the 3.938 bore will get you to 107CI (actually about 106.5CI  ).

3. My thinking was go with the build that I planned (107CI), have it Dyno-SERT tuned, and see what the HP, TRQ, and and Curve look like. Then, if I believed that those elements could be improved upon, I could always modify/change my exhaust setup at a later date. I was unaware of just how poor a performer the Rinehart True Duals would prove to be, especially with the "performance baffles" when it comes to torque and where that torque comes in.

However, overall the bike really runs great now with plenty of HP and TRQ, but shifting the torque curve left a bit might be a little more in line with where I'd like my torque to come in with a heavy bagger thus increasing the "seat of your pants dyno".

Here is a very similar build by GMR Performance producing very similar peak numbers but by using the Fatcat 2 into 1. Check the difference in the overall torque curve and at what rpm the 100 ft/lb mark is reached. The build is a 107CI conversion from a 96CI (bored to 3.938") with Andrews 54s, reworked heads set to 9.8:1.

http://www.gmrperformance.com/index.php?option=com_docman&task=doc_download&gid=34&Itemid=60    105ft/lb at 2250 rpm

Here is the very same build/motor with Rinehart TD's with "quiet baffles", quite a difference in where the 100 ft/lb mark is reached.

http://www.gmrperformance.com/index.php?option=com_docman&task=doc_download&gid=33&Itemid=60    100 ft/lb at 2750 rpm

With my "performance baffles" (least restrictive), I don't reach 100 ft/lb until about 3200 rpm. After speaking with Rinehart Tech Dept., they believe that the "quiet baffle" will get me 100 ft/lb at about 2600 rpm. I think that is a nice compromise and quite acceptable and probably the direction I'm headed! It will cost me $94.00 (baffle) and tweaking my current tune (hopefully 1 - 1 1/2 hours dyno time = $90.00 - $135.00).

Tom

[timtoolman]

hi  tom  ijust did a build similiar to yours,  stock heads but i changed to 1.900 intake valves and 1.72 se. rocker arms.  with 54h cams,  i had a pcv but swithched to tts (ts on its way) i have reinhart slip ons to loud  i put 2.00 fulsacs on  havent dynoed it but wow.  i used s&s 106, with 10:1 comp.  it has the torque!!!!

[timtoolman]

the performance shops that do the heads all say use 88 or 96 cuin heads for performance work,steve at fulsac's says the 09 ,2010 heads flow very well and dont really need much  work at all,

[HD Street Performance]

Believe it or not those big heads drop CCs in a hurry when milled and they flow very well. Not saying the other choice is wrong or bad that would depend on how effective the changes to the stock heads are. I have done them both ways with success.
I am sure it will run fine.

[Tom149]

hi  tom  ijust did a build similiar to yours,  stock heads but i changed to 1.900 intake valves and 1.72 se. rocker arms.  with 54h cams,  i had a pcv but swithched to tts (ts on its way) i have reinhart slip ons to loud  i put 2.00 fulsacs on  havent dynoed it but wow.  i used s&s 106, with 10:1 comp.  it has the torque!!!!

Tim,

Sounds like it will be a fun ride! Mine dynoed at 104PWR and 112TRQ, its a blast. I also went with 1.90 intake valve and 1.615 exhaust valve and welded up the intake and exhaust ports and reshaped them for better flow.

I just need to tweak (quiet baffles) or replace my Rinehart TD's to eliminate the torque dip and move the curve left a bit!

Tom

[Unbalanced]

Tom149,

The only thing I am curious on is the thickness of the spigots and the worry of cracking using a stock cylinder bored out that extra bit to go from 103 to 107.  Yes I know there are some out there and it is becoming more and more popular and that some say it is fine, but was told of one the other day that was .032 thickness and had cracked.   I don't know if this is a one off issue or whether it would be common, guess time will tell.

I have not tried to find the information yet, but wondering what Axtell's thickness  for their 107 cylinders vs. cut stock 96 or 103 cylinders.

[Twolanerider]

I have not tried to find the information yet, but wondering what Axtell's thickness  for their 107 cylinders vs. cut stock 96 or 103 cylinders.

I mic'd them when using Axtell jugs for my 107" build.  Not a spec I immediately remember though.  Will look this evening and see if I still have those notes.

[Tom149]

Tom149,

The only thing I am curious on is the thickness of the spicket and the worry of cracking using a stock cylinder bored out that extra bit to go from 103 to 107.  Yes I know there are some out there and it is becoming more and more popular and that some say it is fine, but was told of one the other day that was .032 thickness and had cracked.   I don't know if this is a one off issue or whether it would be common, guess time will tell.

I have not tried to find the information yet, but wondering what Axtell's thickness  for their 107 cylinders vs. cut stock 96 or 103 cylinders.

The Spigot thickness is a concern, but I was assured that the stock Harley Cylinders should hold up. As you say, "time will tell". There are quite a few after-market 107 cylinders out there that have gotten great reviews, and I inquired about them, but again, I was "assured" I shouldn't have any problems (keeping my fingers crossed).

Tom

[Unbalanced]

I mic'd them when using Axtell jugs for my 107" build.  Not a spec I immediately remember though.  Will look this evening and see if I still have those notes.

Thanks Don

[Tom149]

Believe it or not those big heads drop CCs in a hurry when milled and they flow very well. Not saying the other choice is wrong or bad that would depend on how effective the changes to the stock heads are. I have done them both ways with success.
I am sure it will run fine.

Thanks Don,

I have heard that the SE 103 stock heads can be reworked to achieve positive performance levels as well. There is a fellow here in Colorado (Ken Weber - 10 Litre Performance) that has had success reworking them.

Tom

[Twolanerider]

Thanks Don

Got back here a few minutes ago.  Haven't immediately found those sidebar notes from the build.  If I do later will post them.

[johnsachs]

With a little fluffing,decent valve job,including os intakes,the 103" CVO heads can work REAL good.There's several dynos on the board in the 103" CVO models section.
John

Don't want to be a naysayer,but you could never have me build a stock cylinder with a 3.938" bore.It just ain't worth it.............
I've seen them crack,and out of round from getting too hot.

[Tom149]

With a little fluffing,decent valve job,including os intakes,the 103" CVO heads can work REAL good.There's several dynos on the board in the 103" CVO models section.
John

Don't want to be a naysayer,but you could never have me build a stock cylinder with a 3.938" bore.It just ain't worth it.............
I've seen them crack,and out of round from getting too hot.

Ut Oh ....... ...... John, I hope I am lucky!

Tom

[HD Street Performance]

Axtell pistons (Wosserman) are for a 3.932 bore and set up with .002 clearance

[Tom149]

Axtell pistons (Wosserman) are for a 3.932 bore and set up with .002 clearance

Don,

I think that these are the pistons you are referring to, fairly new product for Axtell:


Squeeze is good:
Axtell Sales has just released 2 new pro-street piston kits for twin cam engines. These 3.932 bore pistons bump a 88 up to 97ci and a 96 to 107ci and can use stock cylinder castings. This 10.25-1 piston utilizes a perimeter dome combined with a re-machined shelf in the combustion chamber to improve mixture burn and airflow. This configuration has proven on our 117 & 124 engines packages to be easily tuned and a big power producer. Axtell will modify your cylinders and heads and can assist you in the design and modification of your engine. Use kit # 800-997 for 4 inch stroke engines and part # 800-115 for 4 3/8 inch stroke late model engines.  


Tom