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Well we all know the problems w/EPA and heat issues with Air-Cooled V-Twins. This is probably going to be the future of Air-Cooled engines, if there is a future. I haven't seen much talk here on it. So I figured I'd stir up some interest and see what you guys think. Here's an article and pics from S&S called "X-Wedge Guts". Good info on the development of this nerw 3-cam engine! Hoist!

S&S X-Wedge Guts

S&S Cycle opened their doors in 1958. At that time, the performance motorcycle business was a lot different. George Smith figured out how a few lighter parts could make a bike go faster and everyone wanted them. Soon he was rebuilding stock engines into drag strip monsters and setting new records at Bonneville. Tuning a bike for absolute performance was the only concern he had. The more performance parts he built, the more the industry wanted. The birth of v-twin performance seemed to come along as S&S grew in reputation. Smith kept pushing forward, developing more and more components that increased performance and replaced their stock counterparts. He was driven to make every motorcycle go faster--a mantra that has echoed throughout S&S history.

As the second generation of Smith family members took the reigns at S&S, a new line of products came to life—almost every performance component you could think of, and then, complete engines. The release of these engines—the 96ci was first— coupled with the extreme shortage of Harley-Davidson® motorcycles brought the business of production custom motorcycles to life. If you were involved in the motorcycle industry during the early ‘90s, you must remember the sheer excitement that crate 96ci S&S engines brought! Suddenly there was a way to build a radical custom with a powerful engine that also offered significant reliability. But that wasn’t enough for S&S. Soon there was the incredibly potent 113ci engine, followed by the massive 124ci. S&S was helping the motorcycle industry grow with leaps and bounds.

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Big Dog Built one of the first X-Wedge customs.

To transition from the second generation to the third generation of S&S leadership, the family embarked on a project the scale of which was never seen in the aftermarket motorcycle world—the S&S 145-Tribute engine. This project, the biggest production engine on the market was a sure way to help the third generation get a solid foothold on the industry. Everyone wanted a 145—and why not? A well-tuned version could deliver close to 200 rear wheel horsepower and the engine came along about the same time as 240mm and 250mm rear tires did— traction was available for the big inch engine and the aftermarket jumped on it.

The production custom world literally exploded at the start of this millennium. This rapid growth and the increased number of custom bikes on the road brought the third generation of Smith family members a whole new concern—tightening EPA laws. Knowing the EPA laws would tighten later in the decade, then S&S CFO Brett Smith proposed a new direction to the senior management team in 2002. Smith, along with former VP of Product Development, Geoff Burgess, wanted S&S to design, engineer and manufacture a proprietary engine that would keep air-cooled, pushrod v-twin fans happy for a long time to come. With the Board of Director’s support, Smith and Burgess sat down with a small group of S&S Product Development team members and explained their thoughts in October of 2002. The plan was to complete the 145-Tribute Project and then push forward on the then unnamed project.

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Smith and Burgess were in agreement on two key ideas. First, the proprietary engine would need design input from the OE manufacturers likely to utilize it in future models and, the 145-Tribute project had been the best way to develop project management skills and expertise to make this new endeavor successful. Recommendations from the OE’s were received during meetings, after which, Product Development team reconvened. Led by Scott Sjovall and Jeff Bailey, the team took the ball and ran with it after the completion of the 145ci project in October 2003. Sjovall, then Manager of Research and Development, had responsibilities throughout the S&S organization, so he was hands on when he could be. But Bailey lived his life through the development of the new engine.

 Scott Sjovall - S&S Vice President of Product Development: The motor is elegantly simple, durable, a pleasure to ride and an excellent foundation for even more performance. I think I can speak for everyone at S&S when I say we love to talk about the X-Wedge and answer questions.

Burgess left S&S for Global Motorsports in October 2004 and, a few months later, in December of 2004, Bailey emerged from the R&D area with a prototype running on a dyno. By April of 2005 there was a prototype in a chassis and running around Viola, Wisconsin. The project internally named “Fred” during the development process was replaced with the formal X-Wedge name during the summer of 2006. In December of 2006, the X- Wedge was introduced to the world in an article written by Kevin Cameron at Cycle World, which coincided with final design input from the OE manufacturers. Shortly thereafter it sprung onto Bikernet.com. During all of this excitement, preliminary testing showed it would easily meet 2008 CARB laws and 2010 EPA laws! To wrap up an already crazy 2006, five X-Wedge engines shipped to the Project X builders in December. A plan to have S&S employees ride to all the major events in 2007 on X-Wedge powered bikes lead to six additional prototypes being built before the calendar rolled over and the formal unveiling took place in early 2007 at both the Cincinnati V-Twin Expo and Daytona Bike Week

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X-Wedge cams.

The all-new S&S X-Wedge (pronounced “cross” or “ex”) is a 56-degree, closed-loop fuel-injected, three-cam, overhead valve v-twin designed to deliver the performance expected of an S&S engine, while complying with EPA laws. Initially, the X- Wedge will go to OE manufacturers of production customs in engine sizes of 117 and 121ci—with larger packages to come later. The 56-degree v-twin utilizes three belt-driven, large base-circle cams; two exhaust cams and a common intake cam achieve almost straight pushrod angles that combine with automotive-style rockers and roller tappets to create an incredibly quiet, EPA noise conscious valve train. The X-Wedge is actually 5db quieter than a 41/8” S&S 117ci engine from 2000rpm through 5000rpm!

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Induction on the X-Wedge is done with the new S&S single- bore throttle body pumping fuel and air into a wedge shaped combustion chamber contained in a head with a five stud bolt pattern and increased fin area for maximum cooling abilities. By design the X-Wedge got its name from its cross-wedge combustion chamber—designed so that the intake and exhaust ports are in alignment with the valve stem plane to maximize performance. The head has the fuel injector mounted directly in it to improve injector aim for even more efficient combustion. A non-structural rocker cover that will allow various OE builders to design a look specific to their brand covers the aforementioned automotive rockers.

The cylinders use the five-bolt pattern, have no oil return holes and are common design for front or rear placement. Their round shape reduces bore distortion and computer designed progressive fin spacing increase the cylinders cooling capabilities. The cylinders are die-cast over the most aggressive liner seen in the industry to ensure heat transfer and permanent adhesion between the cast iron liners and the aluminum that surrounds them.

Naturally case design improvements were implemented including beefier engine mounts, a single oil pump sump location and integral tappet blocks with common front and rear tappet covers. By increasing the crankshaft mass, additional strength is found and vibration reduction is achieved, even when the stroke is pushed out to 4 3/8”. The new S&S X-Wedge crankshaft is a one-piece forged and Nitrided assembly. S&S Product Development team members integrated a side-by-side rod arrangement that utilize plain bearings. The X-Wedge crank is larger than a typical S&S crank assembly and helps to reduce vibration by just over 20% in comparison to a typical S&S 117ci engine.

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Here’s Bill Rucker’s version of an X-Wedge rocket.

The X-Wedge will not fit in a standard frame. Specific engine mounts are required, but it will match up to the common primary and transmission designs currently on the market so OE manufacturers will not have to re-engineer the driveline to utilize X-Wedge technology. Additionally, exhaust design will need to be X-Wedge specific due to the 56-degree configuration, incorporating O2 sensors for the closed-loop fuel injection.


Maxine Wheat - Daughter of Ken Smith: As a member of the third generation of the Smith family, I am proud to say that the X-Wedge is one of the greatest S&S achievements and I believe that my grandparents would be very happy and excited to see the results of so many years of hard work and dedication if they were here to celebrate with us today.

S&S is an almost 50-year old company that is family owned and run. The Board of Directors is comprised of family members in the second and third generation of Smith lineage. Some of the family members have offered quotes that will help you understand the scope of this project. Also included are quotes from key S&S personnel involved in the development of the X- Wedge.

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A few key engineering designs are showcased in the following photos. We used the S&S cutaway engine to give you maximum visibility of this revolutionary engine

Pic: Fred’s flat-top pistons.

S&S 117ci X-Wedge Specs:
Bore = 4.125”
Stroke = 4.375”
Displacement = 117 CI
Cylinder head design = 2 valve Cross Wedge
Valve sizes = 2.0” Intake and 1.6” Exhaust
Pistons = Forged with no notching, common front to rear, .927” wrist pin diameter
V angle = 56.25 degrees
Cam Drive = Gates 30 mm wide system with automatic tensioner
Valvetrain = Hydraulic roller tappet with pushrods
Rocker arm ratio = 1.7:1
Crankshaft = Forged and nitrided one piece
Rod type = 7.400” forged split design with 7/16” bolts
Bearing Type = Tri metal plain style rod and main
Main bearing journal dia.= 2.36”
Rod bearing journal dia. = 2.20”
Oil system = Dry sump with internal gerotor pump
Induction and Engine Management = 2-1/16” throttle body with S&S closed loop VFI
Fuel injectors = 34.8 lb/hr @ 3 bar fuel pressure
Complete engine weight = 163 lbs
Crank and rod assembly weight = 42.75 lbs
4 bolt engine mount system using 7/16” fasteners
Compression ratio = 9.75:1

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Prototype Engine Pic

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Close up view of exhaust flange mount—standard design, new location.

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The X-Wedge has its fuel injectors built into the cylinder head.

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With the Teardrop air cleaner off, a clean view of the S&S single bore throttle body is offered. The X-Wedge has closed- loop fuel injection.

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Intake Manifold

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With almost perfect pushrod geometry; the X- Wedge can use automotive style rockers. All you do is remove the rocker cover—which is just a cover and offers no valve train support—and there is easy access to the rockers.

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The new X-Wedge uses a single-coil valve spring to help minimize valve train noise.

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As you can see, the pushrod tubes on the X- Wedge are huge. Oil runs up through the pushrod, and oil and air are carried back down through the pushrod tube.