OK, I'll hit on a few points then if needed I'm going to lay down some physics eqations to back my points up if needed.

1. The Harley BB 95" kit again does not make everything necessarily equal at all. By adding just the jugs and pistons there is the potential for an increase in chamber cc volume thus effectively lowering compression. Add that, plus one cubic inch, then add the fact that earlier Harley Twin cam heads and the newer ones on the 96" motors are far from identical, you even have to account for the wide discrepancies in head gasket thickness,castings from one HD to the next, even fuel and the tune itself can play a significant role and you have again proven what?

So to keep it simple, still all things are not equal in that comparision as well. THe only way to get an HONEST equal playing field evaluation is to build up 2 motors of the exact same cubic displacement, paying careful attention to every detail from compression, afr management etc. to get an honest apples to apples comparison.

But to further this, I have seen some stock 95" BB kits and to be quite frank, they are very similiar in their hp and tq output to the stock 96" motors still.

2. The exhaust port comment I made was self explanatory. The ports were too large I felt for the engine combination in question I worked on years past. Remember these are hand ported heads, not CNC machine controlled. Ports from head to head can have variances. The valves were also too large in COMBINATION with the porting done. I believe 1.615"s or 1.630" valves were used. Which IMO are way to big for exhaust valves on TC engines under 107" regardless. But many places run exhaust valves in this size. There are a number of reasons for it, one big reason can equate to less time consuming work being done to reshape/port the exhaust valve. Less work means you can churn out more product per week. Thats a fact. Alot of these places, even the very good ones only want to spend so much time per head. Time ='s money to these places. And these places are here to make MONEY. For one of my personal rides I run 1.57"'s cut down and modified. Alot of time was spent on my heads, and the work done on my heads is rarely seen kickin around.

Onto the cam subject briefly.

Lift on cam specs really means little and doesnt state whether a grind is mild or hot. Timing on the intake closing point of a cam is a much better indicator of how hot a cam is for future reference. There are many sites like Nightrider that go into detail on things of this nature. And to add one last thing I dont remember commenting directly on HQ cams........again lots of my statements and posts not being fully read here.

3. They can actually(minus maybe a few hundred rpms lower in the powerband as stated above). But for people to get the same displacement VOLUME, they will again need to remove the engine split the case and BORE the case out. Again an expensive endeavor, many riders aren't willing to do.

I can honestly see why HD did the 96" stroker. It allows for more displacement(which gives more power stock), stroking also will help with gas emmisions as well, but in terms of performance there really is no honest benefit. The 4" stroke on the older 88" and 95" powerplants was/is already a really long stroke in itself. Shoehorning that longer crank in the TC as a stock item is IMO a bandaid fix for the ever increasing emission issue Harley is dealing with from the gov't.

 

Have some experience with strokers having built and rode many over the last 36 years. 85% of the engines that R&R Cycle, Riverside Cycle Machine and Hyperformance build and sell are 4-5/8" stroke. People say "what about piston speed?" We have found that piston speed does not increase with these over the long haul because the earlier torque in the rpm range, the less rpm is used in the riding band. Ask Pistol Pete at R&R about his 139" Bourget that he rode for 5 years with 30 some thousand trouble free miles on it and when he tore it down for inspection it was still good. Ask Reggie Senior about his 49 state EPA approved 155" 4-5/8" stroker that gets 45 miles to the gallon and doesn't go over 200 degrees oil temperature. Ask Paul Matyka about his 160" prostock engines with the 4-5/8" stroke that have been winning drag races all up and down the east coast.

 

randy,
you got no reason to be on the defensive, my friend...we know your stuff WORKS!!!

 

I agree with pretty much all of this. Never said you can't build a rock solid stable undersquare engine(but 30k isnt considered alot of miles on a street engine). And there are plenty of long stroke race engines that churn out incredible #'s as well, but if you dig and do some research on race and street engines with an oversquare design the list will be overwhelming.

Like Ive said, there are many ways to get to the same point. But I think for long term reliability, even an old style engine based on very old technology can highly benefit from a shorter stroke and larger bore arrangement. The twin cam was designed originally with a 4" stroke crank and going beyond that I don't think is necessary at all. I have a 121" TC motor on the engine cradle right now thats going into my winter ridgid chopper build that will breeze through 100k and still put down more than respectable hp/tq #'s, all while being very smooth with minimal vibration through the frame(desireable for a ridgid that will be ridden alot).

 

Randy, you are right on the money and if there were huge advantages to oversquare, that is what everyone would be building. My 4-5/8 stoke has 18k on it this summer since I built it, no oil consumption, gobs of torque and reliable as all get out. No, I dont know of anyone yet with 100k on a long stroke engine, but I'll bet they will get there easily if it was put together properly.

 

Um, just a heads up, pretty much all auto engines today(with the exception of I think a Mazda) and most modern motorcycle engines are an oversquare design as well. That says something in itself. How about Indy F1 race engines? Oversquare and they all rev to about 20k. Nascar? Same. Alot of what HD does is *** backwards/nostalgia. It works, but does not mean its better. I love my *** backwards old style V-twin engine as much as anybody else on this forum, but if I can find a way to improve upon it I will and have.

Again, quite a few people here have taken my words and intentions the wrong way, and thats kind of sad, but it is what it is. And my original point is if your going to split open the case, I would drop down to a 4" stroke and bore the case out. And this can be done reliably on the stock case to a 121" displacement using the stock 4" stroke. Its a hell of an engine. Need more displacement? Then stroke it out, but I only believe a street engine should be stroked as a last measure to gain extra displacement. People seemed to miss that point.

 

speaking of mazda, happen to have a wankel '05 rx8 sittin' in the drive...care to race it?

 

Once I find a suitable chassis to put my Plymouth 340 6er in sure, LOL

 

what was that engine in from the factory?

 

Super, While I do agree with your general theory on the stroke vs bore argument, I don't see it as important enough to change out my crank and de-stroke it. If I do open the case i will replace the bearings and have my crank done up right so it is strong enough to take the beating I give it. If the case is open, might as well bore it. This will lessen the forces on the cylinder walls and help improve the rod ratio. I will also change the compenstor while I'm at it.

I saw a reply on this thread somewhere that said something about the wrist pin being moved up into the ring landings as compared to 88 pistons. You are mistaken (whoever that was). It is my understanding that they used a shorter rod in the 96. This kept the wrist pin down in the piston but may have compounded the effects of the longer stroke on the crankcase and cylinder walls. That is why I figure....if I'm opening it up anyway and if I was going to go with a bigger bore anyway....why not go ahead and make it quite a bit bigger and delete the negative affects of the stroker while increasing overall displacement?