Let's clear something up guys! The reason Super is saying to go with the over-bore instead of stroke is simple:
When you stroke the engine, you add ci's by making the rotating circle larger at the connecting rod. Two things happen when you do this. You get SLIGHTLY (where the stroker=more torque myth comes from) leverage. The other thing that happens is you increase stress on all aspects of the crank. Why? Get on a merry-go-round and try standing in the center....very easy to do....now take just one step out and see how easy it is to stay put....get it? Yes, you can build the engine to take it, but it will be smoother (all else being equal) with a shorter stroke.
If you still don't think so, compare a TC88 to a TC96. I already have, the 88 is smoother and the 96 makes more power. I'm going 107 when I can afford it. Will I have any crank work done? Probably not.

P.S. I didn't mean to speak for you Super, I'm just trying to explain the reality of stroking.

 

A. A "Square" TC motor would be a 4" bore x 4" stroke (100"). The only reason why you see alot of "stroker" twin cams kickin around now is because HD includes these cranks in their engines now(the 96" ones of course). Want to know why? Because its easier for Harley to pass the strick gov't emmisions test using a smaller BORE. The twin cam engine was originally designed at HD as a 95" powerplant using a 4" stroke x 3.875" bore(95" /1546cc). But to pass emmisions(and make more money as an "upgrade")HD ended up going with a smaller bore to help them pass strict emmision standards. The smaller 1450cc bore setup allowed for a slightly quicker combustion burn and retained heat better. Couple this with a rediculously lean tune from the factory(why do you think these bikes run so friggin hot from the factory?)and Harley is just barely passing the gov't requirements.

So after 7-8 years Harley now includes a "larger" displacement engine from the factory in form of a "stroked" 88" twin cam motor. Everything is identical to the 88" minus the crank,rods, and pistons. Allows them to increase engine volume while keeping in gov't emission spec. Now folks who have a 96" stock and want to use the original "95" cylinders actually get a 103" displacement. Following me on this?

Now using the "performance marketplace" as a guideline. You don't see the big picture here. Most people don't know or want to spend the cash(alot more than $1000), to reduce their stroke length and increase their bore for a number of reasons including:

A. They don't know or see the benefit(as most people here or anywhere don't know as much as they think about vtwin engine physics)

B. They don't want to spend the high cost(buy a crank, pay labor to split the case and install)

C. Potentially pay to have their case bored as well

D. Then pay for a new set of jugs and pistons

Most people don't see the cost/benefit of reducing their stroke back to the original 4" setup then boring out their case to increase it back to where the original displacement was or greater. But most people don't know what serious engine building entails now either. They prefer the quick cheaper alternative fix instead.

Whether this be racing or daily use. HP is HP. Whether your running a bagger or not, the ORIGINAL 4" stroke crank is better for power in terms of LONGEVITY. (Ask any competent builder how great it is to have the crank pin moved up into the RINGLANDS like on the HD 4 3/8" crank now used. Not the best design by a LONGSHOT!) And I gave many reasons why above. And any half competent shop/individual can get easy 100/100 # outs of the ORIGINAL 95" TC setup. More than enough to smoke the tires in the first 3 gears on a heavy bagger and still get a reliable 100k out of their build.

Now getting to your buddy Kevin. Like I tell all. Stay away from HD cylinders. They are poor. They wave like spagetti and flex ALOT. The "Bigger bore" 4.065 diameter(or whatever they are)cylinders are a joke. If your buddy is going to spend the money to get his case bored out, then he should look into a pair of Axtell cylinders. They come in 4" bore, 4.125"(107" which is a very popular build around here), and 4.25"(114" which requires a very competent shop to properly bore the stock case out to this size correctly). Any of these setups can easily make 125/125 #'s or better with EASE.

Hell my 97" build (3.938" bore x 4" stroke which needed no case boring)just made 120/125 #'s on a dyno the other day with no AFR/ignition timing tuning whatsoever.

 

Nothing unusual about my build at all. But I will explain a few things about it.

A. At the time I purchased my bike back in 03' I thought my 100th anniversary bike was gonna be something special(boy did I find out otherwise as they made more of them then Honda made cars......), so I basically wanted to keep the stock engine case intact and unmodified(other than adding the Heavy duty Timken crank bearing)and just increased the bore to the point where case boring was not needed. This ended up being a 3.938" bore using all aluminum cylinders.

B. I wanted to use all aluminum cylinders to help REDUCE heat in the engine. Riding friends cannot believe how cool my twin cam engine runs. My oil temps in the oil bag never pass 200 degrees to give you an idea.

C. I knew I could get RELIABLE 125/125 numbers out of my setup with EASE, while most enthusiasts sweat just trying to crack the 100/100 # barrier on a similiar sized build(the popular 95" setup)

D. Yep I run a very high STATIC compression engine. But my actual running compression is lower and my engine was carefully setup(I paid very close attention to combustion chamber shape,squishband clearance,a/f ratio,type of intake used[dual runner in my case which has no reversion characteristics like single runner designs]gearing,plugs used even and timing etc.). My bike doesnt detonate at all on 91 or higher octane gas even while 2up riding.

E. The woods cams I use are excellent street cams, especially when used with a 2 degree advance key. Again it comes down to knowing engines and how to set em up. Most people don't.

Most people go with a more mainstream build, because of lack of information or knowledge on their own part. And to go one further, even most mechanic shops have at best rudimentary information on the design physics of a motor. 99 out of 100 motorcycle mechanics would have no clue wtf I was taking about if I asked them the significance on cam intake open and exhaust closing spec., or the timing spec on the intake close event as well.

 

this is really a good discussion!...I apologize for underestimating your knowledge/experience...still must disagree about h-d 4.06 cylinders...they are way cheaper than axtell, a .005 overbore squares them up, and if headquarters recommends them, I'm sure they've thoroughly tested and found no problems....and I do like very high comp motors like yours...with special care they can be used on the street...would love to see your dyno sheet or 1/4 mile sheet!

 

Yep, HD cylinders are much cheaper than Axtell. And you get what you pay for too. HQ btw does NOT have the best reps for those in the "know" when it comes to TC engines. I have NEVER been a fan of their headwork AT ALL. Every time I have come across of set of heads done by HQ I have been less than impressed.

Axtell cylinders are considered the absolute best on the market, and you do get what you pay for. The shape of their bore is very uniform and exacting. HD cylinders are very poor and flex significantly in comparison. The tolerance differences from the top of the cylinder to the bottom are very significant. Like rippling water by machine spec standards. And besides if your going to spend money to bore your case out, why only go just a smidge over 4"? May as well get the most out of your money and go 107" or 114".

FOr headwork, if you really want to get a good bang for the buck try Dewey, T-man performance, CycleRama or NRHS performance. Any one of these places will give you a much better performing head set up CORRECTLY for you parts combo.

 

Ok I have been reading this thread with eyes wide open. I "thought" I had a clue about what I wanted to do with my ride this winter and now Super has me rethinking everything I "thought".

So, Super...I am confused about case boring now and what it actually is as well as why I need if to go to 107. I'd prefer not to open the cases as it obviously entails spending more $$$. I'm looking for a "bang for the buck" type upgrade over stock.

Heres what I "thought" I wanted so I'm curious now as too what you "reccommend".

I want something 100/100 min, I am almost always riding 2 up, want low/mid range tq say 2200-4500 range. Want it to be reasonable on fuel, say 40mpg. Don't want to have to worry about constant tuning. Currently it is stock 96 with SERT, SE-II Slip-ons the sisters to the 98'bs, stock header, SE A/C. I am willing to go to a dual header but want to retain the SE slip on's, not a fan of the 2-1. I do know if I do anything 103-05-07 I want heads worked on, why waste the extra CI on heads that can't flow.

So if I was asking you for build what would you say? I was a phone call away from ordering either a AMS105 or HQ103.

mps

 

dewey's heads, wood 408-44 or t-man 525 cams, flat-top 103 pistons, supertrapp 2 into 1 (if you want quiet) or bassani roadrage ( if you want loud)...100hp/110tq and won't break the bank!

 

Before I can give an HONEST unbiased opinion, I need to know your HONEST MAXIMUM budget for what you want to do..........I'll give you a good recommendation once I have that budget in hand with a no nonsense answer. =D

 

Well, there are many ways to skin a cat, My Indy shares the same opinion about HQ as you do, but frankly he finaly had to admit that my bike hauls *** is not noisey, gets great milage and makes better than average power.

I would take a set of HQ heads over 90% of the stuff I have seen/used over the last ten years, or anything made by SE, I wanted to do a set from Dewey, but his health issues made me turn to HQ again and i have not been disapointed.

Point for point I agree with your bore/stroke theroy, the T/C platfrom has opened up a great new chapter in HD performance, but only a select few such as yourself could apriecate what you have shared with us. most couldnt even give a rats *** about a 4x4 square engine as long a the one in there bike right now is running, the the chrome is shinny.

I mean, if you think a PCIII is a real tuning device then your not even close to ready for a squared and preped T/C

for me, a little buzz IS nessesary........for the ladies!

 

Yes, there are many ways to skin a cat I agree. But I can't really continue to conversation with you on some of your statements. Your bike makes good power? Honestly? Im glad to hear it. I assume HQ did some of the work? OK. No prob. I'm not saying you can't make power with HQ performed work. But my statement was very generalized. Alot of HQ's own touting and self promotion is bogus. BUt to say noone makes power from incorperating their own work would be a serious injustice on my own part. Im sure someone has found a parts combo that works relatively well with their machine work. But again you made a statement with mot much relative info behind your build(actually none at all other than a basic claim).

But anyway, Im relatively new to this board.....I see ALOT of misinformation/BS, and I feel its OK for me to input my .02 for those who want a good fundamental understanding of their powerplant and want to dispell a ton of myths that surround the TC platform. People can take my .02 as they see fit. I never said you can't make power with a HQ set of machined heads, but I do know that overall there is much better options out there for most people's personal builds. HQ made its reputation on the EVO platform. But IMO they seriously lag behind many other machine shops when it comes to the TC platform. But hey, almost ANYTHING is better than a stock set of EPA restricted heads now right? =D

PS: The PCIII BLOWS, and so does the SE SERT and reace tuner!