The deadline is tomorrow!” the editor grumbled over the phone and hung up.
01. A Branch-O’Keefe reworked Twin Cam head with an 83cc combustion chamber. The smaller
I turned to my associate, the performance editor of Bikernet.com, Ray C. Wheeler, and pointed at his computer. We dropped a gear into the scramble mode and went to work. Fortunately, we have been working with Bennett’s Performance in Signal Hill, California, on a Twin Cam engine build. Even more fortuitous, Branch-O’Keefe shares the same building. John O’Keefe now owns and runs the business and worked alongside Jerry Branch—the legendary horsepower guru and the master of cylinder head airflow, velocity, and volume, for several decades. Jerry was a consultant to the official Harley-Davidson XR race teams among others and involved in the development of the Evolution motor.
Let me back up before the deadline bell rings; it’s not uncommon to receive “reminders” from the editor at 2, 3, 4 a.m. This morning he showed up at the headquarters at 5:45 riding around the gated property for an hour before I got out of bed and met him outside. An exchange of pics was made during the predawn run, and just like that, only a melted-rubber-scented dusty cloud remained in his place.
02. Basic, stock 85cc combustion chamber with limited breathing capacity.
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03. A view from outside the head of the stock, restrictive exhaust port; the valve guide
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04. The exhaust port viewed from inside the head after valve removal. Notice the rough an
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05. A stock exhaust (left) and intake valve from an early Twin Cam. The Factory used the
Ray and I are planning to attend the Bub Motorcycle Speed Trials in Bonneville this coming September with two motorcycles. Ray rode his touring-equipped 124ci fire-breathing ’04 Dyna Glide for 50,000 miles, then rode from San Jose, California, to Bonneville in 2009 and set two records with saddlebags on his bike. Then he got serious and added an Aerocharger turbo charger and rode another 30,000 miles before returning to Hardtails, back in San Jose, for a tune-up.
06. Stock set of double wound springs, with heavy steel keepers on top. The added weight
The Bikernet.com 5-Ball Racing Team convinced Ray to pull the 124-inch monster and put it in a Bonneville-dedicated chassis for 2012. So what was he going to do with his touring Dyna? He replaced his highly modified stock cases with S&S racing cases. Randy at Hyperformance, in Pleasant Hill, Iowa, repaired the Harley-Davidson cases and sent them back to our headquarters. We went to work with Eric Bennett to build him a calm, long-distance, Dyna hot rod touring motorcycle.
We ordered a brand-new RevTech big bore kit that would take the stock 88-incher to 97 inches. We grabbed a Screamin’ Eagle cam plate with hydraulic tensioners for the longest lasting durability and less friction loss. Then we started to search for a lower end and found two reputable Twin Cam lower end rebuilders, one being Dark Horse Crankworks, in Osman, Wisconsin, who swapped the raceless stock connecting rods for I-beam rods with races for much improved heat dissipation and longevity. Plus they replaced and TIG-welded the crankpin into place to remove the chances of flex and slippage, along with balancing the engine to Dark Horse’s secret balance factor for this engine configuration, for smooth running, less vibration, and reliability.
Ray, our hot rod nut, slipped in a nefarious phone call to John, the master builder at Dark Horse, and tried to jack the stroke order from 4 inches for an 88-incher (97 inches with the CCI kit) to 43⁄8 for a 96ci configuration (or 106 with the same RevTech big bore kit). We’re not exactly sure whether he succeeded or not—hang on. The Harley cam drive system also comes with a more efficient oil pump with increased oil volume and flow characteristics, which lends to the overall durability of any Twin Cam configuration.
This engine, designed for long distance, reliable touring was coming together with the absolute best-of-the-best components. Eric volunteered a set of worn stock heads to be rebuilt next door at the nirvana of flow, Branch-O’Keefe command center. The pristine machine shop is lined with heads destined for locations all over the country, Europe, and Japan. John keeps an inventory of more than 100 sets of heads and offers a trade-out for pre-rebuilt heads, for faster turn-around, or he will perform his magic on your set of heads and have them back in the mail within two weeks.
07. Combustion chamber and ports early in the Branch-O’Keefe porting process. The larger
Jerry Branch opened his shop in 1969 and was recently inducted into the Trail Blazers hall of fame. He’s improved the breathing side of champion race team engines ever since. One of his early employees was the young John O’Keefe, who joined the team in 1975, and is still marveled by the energetic 88-year old Jerry Branch. Jerry is currently working with Dan Gurney to build faster cars. John took over the business seven years ago and has kept the high-flow fires burning.
Branch-O’Keefe heads are much more than tried-and-true porting or even welding up and enlarging valve pockets for large valves, reshaping combustion chambers, or shaving heads for added compression. They replace every head-related component with endurance-tested, state-of-the-art titanium valve collars. In the case of late-model Twin Cams, they replace the leaky, spindly, stock valves with stronger 5/16-inch stainless steel valves.
Twin Cam heads from Branch flow about 30 percent better than stock heads across the valve opening range. Actually, stock heads flatten out in one position and don’t flow any additional capacity throughout the remaining valve opening sequence. In that area, Branch heads make big broad-rpm power all the way to redline.
They reshaped the heads through years of trial and error to allow for larger, better flowing valves in the optimum position for complete combustion, since the stock head/valve combination didn’t burn all the fuel, impeding efficiency in the factory engines. The area around the valves became smaller, but they were able to speed up the velocity of the air passing through the ports. In the smaller areas of the head, they were able to add more space around the valve.
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08. An example of a polished intake, with a microscopic, fish-hook finish for maximum air
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09. Black nitride intake valve held above the intake port and valve seat—its eventual mat
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10. DYKEM Blue was spread on the valve seat to visualize the results of Branch-O’Keefe ha
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11. Nearly finished. Both ports have been polished while the intake valve set is awaiting
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12. A view of intake port from outside the head. That’s a huge difference compared to the
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13. Fresh valve guides offer precision fitment with the new valves.