Make Mine a Triple: The Feuling W3

Supersize your V-twin with an extra cylinder. From the October 2000 issue of Motorcycle Cruiser. By Evans Brasfield.

The story is as old as the internal-combustion engine. Some people are never satisfied with their engine's power output. What follows is a slippery slope of bigger bores, capacious carburetors, obnoxious exhausts, radical valve timing, and demon tweaks. Even when the engine has obviously reached the ragged edge, a few builders will push ahead, testing the boundaries of physics--and common sense--to produce very powerful, very expensive grenades.

Jim Feuling, owner of Feuling R&D; in Ventura, California (, realized that, while nothing exceeds like cubic inches, the current crop of big-bore kits for Harley-Davidson's V-twins were reaching the upper limits of practical power generation. Feuling decided that, in order to add a new wrinkle to the displacement wars, he wanted to build an engine with 50 percent more displacement than Harley's Twin Cam 88 with the 95-cubic-inch factory upgrade kit installed. The result of Feuling's idea takes the form of the working prototype shown here. Looking strangely familiar yet completely alien, the Feuling W3 may be the shape of things to come for those who fancy power cruisers.

Feuling's creation is at its core both incredibly simple and maddeningly complicated. Simply put, why not just graft an additional cylinder onto Harley's robust Twin Cam design? The result would be the desired 50 percent increase in displacement while utilizing parts that are widely available from either H-D or the aftermarket. The complicated part would be, well, actually acting on the idea. This stumbling block, however, wasn't a problem for Feuling.

Feuling holds more than 100 patents in the automotive industry, with R&D; contracts with companies such as Cheverolet, Oldsmobile, Ford, Chrysler, Nissan, John Deere, and Harley-Davidson. He developed four-valve heads for Harley-Davidsons and later sold the rights to Ultra Cycles. He also designed an engine for American Honda's high-mileage streamliner that delivered a whopping 500 mpg at 55 mph. He holds several land speed records, including one for a motorcycle streamliner at 333.847 mph set on the Bonneville Salt Flats on October 20th, 1999. Feuling R&D;'s 28,000-square-foot facility is chock full of CAD/CAM/CAE machinery, making the company one of the few private facilities in the world that can design, test, and build entire vehicles (including the engine and drivetrain) under one roof. The W3 engine project initially began in conjunction with Harley-Davidson, but as the design reached the end of the initial stages, Harley opted out. With the withdrawal of Harley-Davidson, Feuling went back to the drawing board. The original design had been structured so that H-D would need to add just six new part numbers to its inventory. When Harley opted out, that concern was scrapped in favor of a design that used only parts available in the aftermarket plus a few application-specific items that could be manufactured by Feuling.

The working prototype W3 engine we rode is, when viewed in broad strokes, essentially the same as the version scheduled to be sold early next year. Between the time that the bike was shot and the time we went to press, the displacement jumped from 142 cubic inches (2327cc) to 150ci (2458cc) as a result of the bore and stroke changing from 4.0 inch (101.6 mm) bore and 3.875 inch (98.4 mm) stroke to a perfectly square 4.0 inches by 4.0 inches. Taking inspiration from radial aircraft engines, a central, master connecting rod with two slave rods, one on each side of the central rod, direct the 4.0-inch slugs through the cylinders. Feuling tells us that the design has already been tested in a 185-cubic-inch (3032cc) form and a 245-cubic-inch (4015cc!) drag racing kit may also be built.

A trio of Dellorto 40mm flat-slide carbs complete with velocity stacks feed the hungry cylinders. However, the W3 doesn't just count on three big jugs for its power. Several other Feuling innovations make their way into the mix. Feuling-designed cams operate pushrods for the two-valve patented "Max Flow" heads and valves to speed the combustibles into and out of the arena. Staggered triple AR (Anti-Reversionary) exhausts minimize the backwards flowing pulses that disrupt the movement of gasses out of the cylinder. Three Feuling-designed CVX mufflers allow maximum flow through while keeping the noise and backpressure to a minimum. How does a claimed 150 horsepower at 5000 rpm and 195 foot-pounds at 3000 rpm sound to you? The engine is so mildly built that it can even run on 87-octane gas. The aftermarket helps the W3 put the power to the pavement. A Barnett "Clutchzilla" transfers the horsepower to a Jim's five-speed transmission.

A modified Dyna frame wraps around the big engine. The front of the downtubes were widened, and the fork was raked out to 34 degrees, giving the third cylinder a little breathing room. Famed customizer Jesse James of West Coast Choppers ( created fenders and a gas tank worthy of gracing such a unique machine. The almost invisible ghost-flame paint scheme comes courtesy of Ultra. An inverted Storz Ceriani fork ( adds to the aggressive stance of the chassis. Progressive Suspension shocks keep the back end in line. The rolling gear features a 19-inch Performance Machine Trespasser front wheel and a matching 16-inch rear. The dual four-piston PM calipers offer tremendous stopping power, while Dunlop K591 tires provide the adequate stickiness.

Thumbing the starter button brings the beast to life, and the first impression is that of the exhaust note and cadence. You won't hear the H-D potato-potato from this bike. Instead, the engine has a distinct Ducatiesque sound (due to the 90-degree separation between the front and rear cylinders, no doubt) with Harley overtones. Open the throttle and the intake honk of the trio of Dellorto carbs can be heard along with the throaty, yet not too loud exhaust. The stout pull on the clutch lever is only surpassed by the strength required to turn the throttle. In an effort to lessen the throttle effort a full-turn throttle was mounted, making it difficult to roll on the throttle past half-way without choking up on it drag racer style.

Perhaps the long throw of the throttle is a good thing since cranking it wide open in second gear caused the Dyna frame that we rode to flex noticeably under the strain of the 150 horsies. According to Feuling, the next generation prototype will mount rigidly to an FXR frame, eliminating this issue. Since the W3 engine runs eerily smooth at cruising speeds, swapping the Dyna's vibration damping for solid mounts shouldn't present a problem. Unlike many of the ultra-big bore twins we've ridden, the W3 works well in the lower rpm range with none of the surging and drivetrain snatching we've experienced on some aftermarket engines. The engine felt comfortable, even docile at sedate speeds. However, acceleration at any more than half-throttle makes short work of any straight sections of road. Fortunately, the big Performance Machine brakes scrub off speed effectively, giving us an excuse to rap on the throttle once again. W3 owners will, however, want to pop for some stickier rubber in order to harness the bikes acceleration and braking forces; just don't expect the tires to last too long.

Whether the W3 engine configuration is the shape of cruisers to come remains to be seen, but we're certain more than a few twisted enthusiasts will pony up the $20,000 for Feuling's "Warlock" engine and frame kit when it's available. If you can't wait, build your own. Feuling's estimates his expenses for developing this first streetable prototype are mere 2.5 million dollars. We certainly wish Feuling the best and hope we'll get a shot at a full test of the W3 when it's available. A single afternoon in the saddle only whet our appetites.

Editor's note: Jim Feuling passed away in December 2002. The company lives on and still lists the W3 among its products.


Price: $20,000 approx.

Type: air-cooled, 3 cylinder 45 degree x 45 degree

Valve arrangement: OHV; 1 intake, 1 exhaust per cylinder, pushrods, hydraulic adjusters

Displacement, bore x stroke: 142 cu. in. (2327 cc), 4.0 in. x 3.75 in. (101.6 mm x 98.4 mm)

Carburetion: 3, 40mm Dellorto flat-slide

Transmission: Jim's 5 speed

Chassis: Modified Harely-Davidson Dyna

Front suspension: Storz Ceriani

Rear suspension: 2, Progressive Suspension dampers, adjustible for preload and rebound damping

Wheels: Performance Machine Trespasser aluminum, 19-inch front, 16-inch rear

Contact: Feuling Motor Company, 2521 Palma Drive Ventura, Ca 93003, (805)650-3406,

Photography by James Brown (email
Get hard on the gas and the W3 delivers enough power to the drive belt to twist the modified Dyna frame. The Progressive Suspension handles the bump absorption duties well. The Dunlop K591 just doesn't offer enough grip to keep the rear tire from spinning up during high-rpm shifts in the lower gears.