There are custom motorcycles, modified bikes, and restored masterpieces. Then there’s this tour de force built around a 1921 Ace four-cylinder engine. Originally, this power plant sublimated the Hollywood movie industry on a MGM sound stage.
“They used it to create the sound of cars, motorcycles, racecars, or airplanes passing,” said Don Whalen, the owner. 
In 2004, Don traded a ’47 running Indian Chief for the Ace project and began an extensive historical investigation and search for parts. 
Don and his mechanical genius partner, Rodan, decided to replicate William Henderson’s World’s Fastest Motorcycle. Bragging rights were competitive nirvana in the early ’20s as internal combustion technology exploded. William Henderson built 4-cylinder engines under the Henderson name until Excelsior bought his brand, but he wasn’t comfortable with the Excelsior-Henderson structure. Within a brief year, he escaped with his top engineer and their racing pilot, “Red” Wolverton. William formed ACE and was bent on developing a faster motorcycle. They lightened many components, and searched out the aluminum manufacturer, Alcoa, to build state-of-the-art magnesium cases.
William Henderson was the first motorcycle manufacturer to purchase a horsepower-reading dynamometer. Unfortunately, he was killed in 1922, but his hell-bent-for-glory engineer, Everett De Long, with Arthur Lemon took the lightened reins.
As soon as the short-coupled racer was ready, they hauled it to Altoona, Pennsylvania to compete in the 1923 hill climb nationals. They kicked ass, and Henderson convinced the local cops to allow him to make a speed test run on a new, unused asphalt street in town. He hit the amazing speed of 130 mph, and suddenly his Ace was elevated to top ranking (the former record was 108 mph).
Rodan is an SCTA Bonneville official and has been setting records on the salt for over 30 years. He loves mechanical and fast. For over three years, he rebuilt the ACE four cylinder engine, hunted and refined every part, and short coupled the frame.
“I married this project,” Rodan said. He read everything he could find on William Henderson, Ace, and in-line 4-cylinder engines.
“The frame was drug out of a river bed,” Rodan said. “I started with a dented and rusting frame, half the front end, bent handlebars, and the engine.” 
Rodan cut the neck casting away from the Ace frame top gusset tubes and discovered tubing filled with bronze to stiffen the chassis. He bored each frame arm out, then chiseled out the soft bronze (he made chisels the radius of the tubing) until he could heat the tubing and separate it from the casting. The cast-iron neck had to be completely cleaned, with chisels again, before he could braze in new frame tubes. In the lengthy process, he shortened the two top tubes to give the frame the short-coupled configuration. He also raked the frame so the chassis and the tanks were 2 inches shorter than stock, but the wheelbase remained stock.
Hang on for the front-end rebuild. The front end needed to be straightened. The top tree was the casting at the center of the bars. Two cap nuts held the bars and the tree in place. They screwed into the legs, but the threads were shot. Rodan studied the threads with a thread gauge, and then made a tap by hand. He tapped the legs and made two cap bolts. “I ended up making more that half of the parts on the bike,” Rodan said. Let’s touch on what he endured to rebuild the engine.
“The engine and transmission were permanently coupled,” Rodan explained. “I had to remove the transmission, before I could dissemble the engine.”
The gears were in good shape, but the engine needed a complete rebuild.
“I sent one piston to Ross pistons,” he continued. “They manufactured modern forged replacements with total seal rings to fit the old no-oil ring configuration.”
Rodan cut the Ross units down, and also raised the compression slightly. “We also changed the wrist pin diameters,” he said.
Rodan carefully brazed, welded, and filed new cooling cylinder fins onto the old cylinders. The rods ran on babbitt bearings. It’s a soft bearing material poured between a piece of tubing the size of the crank and the rod. Then the babbitt material is cut in half for the rod cap, ground and machined for clearance and fitment to the crank. The rods are bolted to the crank with Prussian blue die on them, rotated, dissassembled, and the high spots scraped off. This process was repeated several times until a perfect fit was achieved.
Rodan rebuilt the clutch by welding new tabs on the steel-on-steel clutch plates, then hand-filing each one to make them fit. The inside of the clutch drum also needed hand-filing.
The list goes on. Rodan made all of the brake linkage, but the rear hub presented a tough obstacle. He had to find and replace the Timken style bearings and hand-made the axle. The stock configuration held two exterior rear brakes on each side of the hub. Rodan eliminated the left side by machining off the teeth. He made the brake on the right and bought a blank sprocket, which he had to bore out and hand-file the usually broached teeth. He made the exterior brake drum using an old interior brake drum, machined to fit.
“I made everything on this bike 7/8 scale, to give it a tighter, more diminutive look,” Rodan said. Then he lightened each part. “I got a new appreciation for the inline fours,” Rodan said. “They were magnificent, so I tried to make this a tribute to the famous Altoona four.” I could ramble on and on about this build. The seat was fashioned leather over a pressed and steamed wooden form in Texas, at Troxel seats. Rodan hand-made all the linkage and mounts. The four tank straps were hand-made, too. “Each one is different,” Rodan said. “They don’t interchange.”
William Henderson was killed on his last new model while riding across town to a photo shoot in December 1922. “He was T-boned,” Rodan said.
In 1927, Indian bought Ace and started to manufacture Indian fours, initially with Ace engines. And so the history of the magnificent inline fours continued.
