Step 4: CNC Ported Cylinder Heads

S&S® now offers a CNC porting service for stock cylinder heads for 1999-up Harley-Davidson® big twin engines. This is an economical way to get a substantial horsepower increase while maintaining a stock appearance.

S&S has developed high flowing intake port, exhaust port, and combustion chamber shapes for stock cylinder heads. S&S then digitally reproduces them in a stock head casting with our 5 axis CNC machining centers. After CNC porting, heads are assembled with new one-piece, forged racing grade stainless steel alloy, valves, valve guides and high performance, conical single coil high silicon alloy valve springs.

Shown is the S&S CNC machined intake port before the valve guide is installed. Notice the raised vane ahead of the valve guide hole. The purpose of this vane is to split the air stream ahead of the valve guide to reduce turbulence and increase flow.

FITMENT

Available for 1999–up big twin engines
Ideal for 88"–124" engines (must use Screamin' Eagle® high flow injectors, H-D# 27796-08, with kits over 106")

FEATURES & BENEFITS

CNC machined ports for a consistent performance increase from stock heads
Great throttle response, high velocity port without losing low RPM torque
Assembled with performance valves and springs ready to bolt-on
Choice of .585" or .650" lift valve springs
Combustion chambers are available in the following volumes:
- 83cc-Generally used for stock 88" up to 106" engine displacements
- 85cc- Same as stock Twin Cam 88" and 96" engine displacements
- 89cc- Recommended for up to 117" engine displacements
- 90cc- Generally used for 124" and up engine displacements
Available in factory black or silver

SERVICE OPTIONS

Exchange Service
- CNC ported heads are available for immediate delivery, core charge of $450 per set must be paid
- Stock heads sent to S&S
- Core charge credited if customer's returned heads pass inspection (see notes)
- 89cc- Recommended for up to 117" engine displacements
- No turn-around delay
Rework Service
- Stock heads sent to S&S
- Get the same set of heads back with CNC machined ports
- The best option for heads with a special cosmetic treatment
- Allow 2 week turn-around
Custom CNC Port Duplication
- S&S can digitize your port design and machine it in your heads, ask an S&S customer service representative for details

Notes:

Only cylinder heads that are in good condition and have “like new” appearance, may be exchanged. Heads with non-OEM compression release machining, superficial damage, peeling or discolored paint, or other cosmetic alterations are not acceptable for exchange, but may be reworked. Rework will take slightly longer than exchange service. Customer will be contacted to review options if heads do not pass inspection.
CNC porting is not available for previously ported heads, heads that have been structurally damaged, or heads that are determined to be unserviceable during initial inspection. These heads will be returned to the customer without modification. In these cases, the customer will be notified and options will be reviewed. New, CNC ported stock heads or S&S heads are available for purchase.
Due to variations in stock cylinder head castings, all inside surfaces of the ports may not “clean up” during machining. As a result, the inside of one or more ports may not appear to be completely machined. This does not effect performance and is not considered a defect.
CNC porting is not currently available for Harley-Davidson® CVO engines or Screamin' Eagle® cylinder heads.

Digitized port shapes are faithfully reproduced in any stock Harley-Davidson® cylinder head on our 5-axis CNC machining center. Intake port, exhaust port, and combustion chamber are all modified. This head will be assembled with new forged stainless steel valves and high lift valve springs to complete the package.

		Stock Harley-Davidson®	CNC Ported by S&S®
Valve Size	Intake	1.805"	1.900"
Valve Size	Exhaust	1.575"	1.610"
Max Valve Lift		.585"	.650"
Max TDC Lift	Intake	–	.230"
Max TDC Lift	Exhaust	–	.215"
Port Flow*	Intake	216.2 cfm	248.6 cfm
Port Flow*	Exhaust	191.8 cfm	209.7 cfm
Compression Ratio	88"	9.0:1	9.2:1
	95"	9.2:1	9.4:1
	96"	9.2:1	9.4:1
	97"	9.7:1	9.9:1
	103"	10.1:1	10.3:1
	106" Big Bore	10.0:1	10.2:1
	106" Stroker	10.1:1	10.3:1
	117" DD Piston	10.0:1	10.2:1
	124" DD Piston	10.7:1	10.9:1
Chamber Volume		85cc	83cc**
Flow testing performed on a SuperFlow® 1020 flow bench at 28” of water test pressure at .600" lift. Heads tested are 2006-upstyle. *As a general rule of thumb, for every 1 cc change in chamber volume equals a .1 increase in compression ratio.

The CNC Difference: The dyno chart compares a stock 2009 FLHT (black curves) with the same bike after an S&S 106" Big Bore Top End Kit, 585 cams and S&S slip on mufflers, and an S&S teardrop AC were installed (blue curves). The top (red curves) show the same engine after the heads were CNC ported and a 58mm throttle body was installed. Both 106" engines perform much better than stock, and are pretty comparable to each other until about 3500 rpm. At that point the engine with CNC heads continues to increase in torque and horsepower because it can still get enough air.

Choose The Right Cam For You: This dyno chart compares a stock 96" 2009 FLHT on the same bike with an S&S 106" Big Bore Top End Kit with CNC ported heads, S&S slip-on mufflers,performance intake, and two different cams. The blue curves represent the 106 with S&S 551 touring cams and S&S teardrop air cleaner on the stock 50mm throttle body. Great torque for performance touring applications. The red curves show the S&S 585 cams with a 58mm throttle body. The increased duration of the 585 reduces low and midrange torque, but the combination of more aggressive valve timing, higher lift and a larger throttle body significantly increases usable rpm and top end horsepower. A good choice for lighter bikes and racing applications. Both engines were tuned with Screamin' Eagle® Race Tuner.

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