Last year I had installed S&S's "106 BB kit, 551 cams and a ThunderMax w/ Autotune. I already had SE A/C and V&H ProPipe. Before that mod crank runout was 0.0035; I have not yet re-checked it. My primary goals are a high torque and very reliable motor.

Current motor is super strong and runs like a dream. Bike has 22k miles. BB/cam install has about 4k miles. Generally I ride 3-4500 rpm.

Now I'm thinking about heads and TB. What makes sense? Seems options involve port and polish HD heads; port & polish or bigger TB; S&S heads (I'm sticking w/ S&S.) How much will a quality P&P of OEM heads cost? I'm a bit hesitant to P&P the OEM heads if that's close to a grand because new S&S heads are around $1,000 and they offer much more. Is it dumb to P&P OEM heads or install S&S heads w/out going to a larger TB?

 

I would have your oem heads worked rather than ordering the S&S heads. That way you can tailor the head work to your exact build as opposed to ordering "off the shelf" heads. Local builder I use runs around 1,100 bucks for his head work and it's worth every penny. That being said since the rest of your build is all S&S parts their heads might be a great match for what you got. As far as do in heads but not throttle body, I don't think that is dumb at all. Lots of bikes running stock TB with head work.

 

I had the same set up as you did except i had 583 cams. I got my heads redone by Hammer Performance and went up to 585 cams. Thing runs like a champ. My power band is much higher now though, which is the only thing i don't like. It does'nt start producing scary power until above 3500 rpm.

 

No need for larger TB for power between 3000-4500rpm. A buddy of mine did a S&S106 kit with ported OEM heads and a Tman 555T cam and is making 123ft lbs of torque in that rpm range and is very pleased to say the least.

 

The oem heads if properly reworked will out flow the s&s heads out of the box. On the other hand if you rework the S&S heads, lookout they will flow some pretty good numbers and make big power. Any head run as cast is going to need work to have good clean flow. The oem heads properly rework will give you the best performance per $. And much better performance than a stock S&S head.

 

Thank you for your comments.

I am surprised to learn that worked OEM heads outperform "stock" S&S heads. Did not realize stock S&S heads could be improved with more work. What additional work can be done to improve the stock S&S heads? Polishing?

It seems that many folks are adding larger TBs, but this thread is saying, for my goals and build, improving the heads does not also "require" a larger TB. (I thought those mods go together) How are output, low rpm rideability, and reliability affected by larger TBs?

If I add tweaked heads will I be asking too much of the stock, unwelded crank that already had 0.0035 runout?

Thanks again.

 

We would suggest to re-work your OE heads, and modify the intake manifold of the OE t/body.
Scott

 

be carefull who does your stock heads for the .551 cams.doing the normal headwork most shops do,the heads will actually be fighting the cams(working against each other)make sure their done for your cams & build

 

Talked with S&S today about this. I was told that if I want to stick with a torquey and reliable motor (yes) I should keep the 551 cams and not allow the compression ratio (CR) to get above 10-1.

I have two basic options from S&S: tweak my OEM heads for ~$800 or buy new S&S 89cc heads for ~$1,000. Claimed better flow from the S&S heads, and cooler running b/c of more fins. On my build, the 89cc heads give a CR of 9.7-1. Either of these options would move the flow limitation from the heads to my stock 50mm TB, so the next step would be the TB. If I use an S&S TB, I should pick a 58mm Throttle Hog (~$350) and red SE injectors (~$80 each).

Given my desire for tq and mid-band engine rpm, I was told not to polish TB or heads, because rough surfaces favorably break up molecules at lower engine speeds.

S&S guesstimated this build ("106 BB, 551 cams, 89cc heads (out of box), 58mm TB, T-Max and V&H ProPipe) would produce ~110 hp and 120-125 tq, and would be very reliable. He said my 0.0035 runout should be fine.

 

If you're the kind of rider who's satisfied with the performance of your stock late-model Harley-Davidson® bagger, stop reading right now, and use this brochure to line the bottom of your parakeet cage. However, if you want to go really fast, read on!

It's common knowledge that to make more power you need to get more air into your motor. That's what the new Throttle Hog throttle bodies are for. More Air. If you have a large displacement fuel injected engine with throttle-by-wire, you need a Throttle Hog!

Throttle Hogs are available in three sizes: 58mm, 66mm, and the giant 70mm. The 58mm is recommended for street engines up to 110 cubic inches and is perfect for our 106" big bore kits. The 66mm is recommended for engines with stock style heads, with round intake ports, of up to 125 cubic inches. That makes them ideal for our 124" Hot Set Up Kit® or T124 engines. The 70mm Throttle Hog is specifically for large displacement engines with S&S B2 special application cylinder heads. That means the port ends are machined with the oval port shape to match the ports on the heads.

The manifold end of Throttle Hogs with 58mm and 66mm bore diameters are machined for stock height engines. The 70mm B2 throttle body is designed for 145" engines but requires customer alteration to accommodate smaller engine heights.

Special S&S Stealth air cleaner kits are available for Throttle Hog throttle bodies. Use your stock air cleaner cover or choose one of the S&S covers. Get maximum cosmetic flexibility as well as maximum performance. Go fast and look good doing it!

Here's how it works. In order to make your throttle-by-wire system work effectively and dependably, we need to use the stock electronics from your current throttle body. So S&S requires that you send in a working Harley-Davidson® electronic control throttle body. Your stock unit will be tested to make sure it works correctly. Non-functional stock throttle bodies will not be accepted. Once we know your electronics are OK, we will transfer them to your new Throttle Hog, and you are ready to have some fun! You're new Throttle Hog will typically be shipped within 2–3 days of receipt at S&S.

S&S® Cycle, Incorporated warrants the S&S components of your Throttle Hog throttle body to be free from defects in material and workmanship for a period of one year from the date of purchase by the original consumer customer. If any parts become defective during the warranty coverage period, S&S will, at its option, repair or replace any, or all, defective parts. Repair or replacement of defective parts is the sole and exclusive remedy.

In the event that any OEM component re-utilized in the assembly of the throttle body fails, S&S may service the unit
provided the OEM components are supplied to S&S at the time of service.

The following parts will also be required for the S&S throttle-by-wire Throttle Hog throttle body.
• Screamin' Eagle® Pro high flow injectors H-D® PN 27796-08
• Intake Manifold Flange H-D® PN 27059-05A (2pk) (58mm & 66mm Only)
• Intake Manifold Flange Seal H-D® PN 27035-05 (2pk) (58mm & 66mm Only)
• Intake Manifold Flange and Seal Kit S&S PN 16-0250 (70mm Only)
• A performance motorcycle tuning module. S&S recommends Dynojet® PowerVision, or Screamin' Eagle Super Tuner


This chart compares air flow of a stock throttle body to the S&S® Throttle Hogs. Tests were performed on a SuperFlow® 1020 flow bench at 28 inches of water test pressure. Throttle bodies were tested with backplates only, no air filter or air cleaner cover. It's easy to see the difference.


* Size *Part Number *Price
*58mm* *160-0034 * *$349.95
*66mm* *160-0010 * *$374.95
*70mm* *160-0039 * *$675.95
**Sold on exchange only! 2–3 day turnaround.**