Many good choices out there and I agree with the pick parts that complement each other. HQ, Baisley, Branch, Hillside and many more are good choices. I prefer the high velocity, high compression route myself with tight quench and a steel head gasket so no pinging issues. The kits I like to use along with having great power rev very fast, start very easy, and run cool. The heads are the oem's cnc ported to take out the core shift and are very repeatable. R&R Cycle also has their own casting with the larger 1.800" intake port that allows the power to keep on climbing.

 

Thanks for the information and the constructive criticism. I do realize that Branch does some excellent headwork and HQ does some excellent piston, cylinder, head, and cam work/kits. Weather it was a good idea or a bad idea; I decided to do this build using as many HD/SE parts as practical. To make a long story a little shorter, I’ve had a very difficult time getting any accurate technical information/specifications on the stock HD and/or Screamin Eagle parts. I discussed what I was looking for with some local, supposedly knowledgeable and trained, HD people and they claimed the Pro 103+ heads were the hot setup. I originally planned to use the 10.5-1 pistons but was told the flat top pistons would provide good performance without the various issues associated with running a high compression motor. They also claimed the stock twin cam heads have a 95cc combustion chamber so there would be little difference in the compression ratio (somewhere between 9.2-1 to 9.3-1) using the Pro 103+ heads with a 98cc combustion chamber. I now know that info cannot be correct but still don’t know the combustion chamber volume on the stock twin cam heads. I figure it must be around 85ccs. To figure the static compression ratio I originally used the formula taken directly from the Head-Quarters website, COMPRESSION RATIO (cylinder volume + chamber volume) / chamber volume. 845cc + 98cc /98cc = 943/98 = 9.622. I more recently used some other static compression ratio calculators that also consider the head gasket thickness and deck height and got between 8.5 and 8.6 which I believe is more realistic. I finally called Keith at Head-Quarters and I agree he is the first truly knowledgeable person I’ve talked to since I started this whole thing. Anyway, to get the best performance out of the Pro 103+ heads, I’m going to use the Pro 103+ 10.5-1 pistons and for a number of very good reasons he highly recommended that I use the HQ-500 cams and not the HQ-575. I just recently borrowed a copy of the Screamin Eagle Pro Racing Parts Catalog, so now at least I have a little more information than when I started. Again thanks for the input.

 

I forgot one other thing. The comparison (on the HQ website) of the SE-255 cams vs. the HQ-500 cams is a convincing argument for using the HQ cams with SE parts.

 

glad you got it sorted out...you should know that tuning is going to be critical with 10.5 compression and hq500 cams...do you have a good tuning center near you?

 

for a number of very good reasons he highly recommended that I use the HQ-500 cams and not the HQ-575. I

What were these reasons? heavy bike, 2 up riding!

with bigger valves and springs that can handle the lift, I cant see why you wouldnt run the .575s.

 

I had several discussions with Kevin at Head-Quarters and really didn’t have the time to go into all the details. I’m not an engine builder, head designer, or expert in fluid dynamics so you’ll get my minimal technical explanation of our conversations. I also thought the HQ-575 would be the best cam for my build based on the combustion chamber size and larger valves. But in this case cams are not like dicks, bigger is not always better. With that said, to get a complete fill on intake I figured it would be best to open the valve farther and keep it open longer. Kevin said you need to also consider the intake charge velocity in that equation. You may actually get less fill/charge for a longer time at a lower velocity than a shorter time at a higher velocity. In this case if the lift is decreased the velocity through a smaller opening is increased. Also the lobe placement (the points at which the valves open and close), valve timing duration, overlap, LSA, LCA, etc, etc, must also be considered. He said with the HQ-500 I’d get more torque at a lower RPM than the HQ-575 and maybe I would have a slight decrease in HP at a higher RPM. Since I really don’t care about a small HP lose at 6000 or so RPMs, I’ll take the torque increase at a lower RPM. Since I don’t have the technical knowledge, experience, or design expertise to argue the point with him, I decided to accept his recommendation and go with the HQ-500.

 

SKYHOOK - The closest good tuner is Thunder Tower HD in Columbia SC.

 

I agree with Keith, the velocity is down with those heads so lifting the valves fast and long would hurt torque, those heads also have less quench area which aids in pinging and tend to run hotter than what I like.

 

Since this piston is specifically designed for use with this head I would hope the engineers at HD actually gave the squish/quench some thought. I would also hope that the piston dome design increases the turbulence in the combustion chamber and not decreases it. Of course these same engineers/designers gave us the can of rocks cruse drive transmission and the incinerate your crotch/head gasket eating SE 110” twin cam motor. Anyway, this 103+ stroker piston obviously has less flat surface area (on top of the piston) and the head has a hemispherical combustion chamber. I believe this is correct but I’m sure if not someone will correct me – these pistons are designed with a squish band around the outside top of the piston that matches the combustion chamber design at the same point. With that said, I don’t know what the clearance is in that area or how to figure squish/quench for this combination. I would appreciate any information that would help me better understand this subject. I certainly understand how important it is to keep heat and the potential for detonation at a minimum. I also understand how critical good tuning is going to be with this setup particularly the ignition timing.

 

This is the paradox, domes slow down the burn, hemi chambers slow down the burn (I'm going to get burned for that one), taking away squish area slows down the burn. On our drag bikes we use flat top pistons, some porters have to sacrifice and use a 30 degree dome (because of their valve angles) to get compression and set the squish to the angle.
I have been out at R&R Cycle when they were doing emmission tests with 5 gas analyzers and a scope testing by products for each cycle and when they welded and increased the squich area the hydrocarbon levels went way down proving to them the importance of the squish area. So when we stage 4 the SE heads and the S&S heads we weld the combustion chambers to tighten up the quench.