VL. Beyond Racer Road 6 – Dark Secrets Revealed

Posted 1/16/2017

I’m calling this “Beyond Racer Road 6” although it’s not officially a Beyond Racer Road article. The full title in the June 1977 issue of Cycle magazine was “The California Hot Rod’s Darkest Secrets.” No mention of Racer Road. I don’t know why – it’s completely in keeping with the other Beyond Racer Road stories. I’m taking the liberty of adding it to the Beyond Racer Road series in this blog and if Cook doesn’t like it he can tell me. This is re-published with permission of the author.

Another difference is this article was mostly pictures so instead of scanning in the text as a photo I re-typed it. It should make it easier to read. The images are scanned from the original issue of Cycle magazine. For reference the first five Beyond Racer Road articles are:
BBR1 – The Toe Gets Dipped
BBR2 – Learning the Craft
BBR3 – Overdog
BBR4 – A Square 4 Two-Stroke
BBR5 – the Hot Rod is Born.

Enough from me, here’s “Beyond Racer Road 6 – Dark Secrets Revealed.”


By Cook Neilson

headertextAll right Duck lovers, gather round and we’ll tell you how our Ducati 883 “California Hot Rod” happened to win the Superbike Production race at Daytona this year. Loyal readers will remember our feature story on last year’s season: the bike’s third at Daytona, its DNF at Laguna Seca and second at Riverside [See Beyond Racer Road 5 – the Hot Rod is Born]. You will also remember the skein of transmission difficulties we had during the ’76 season, and all the effort expended by Bob Gorsuch and Phil Schilling to alleviate the problem.

Nothing worked; the thoroughly-massaged factory close-ratio transmission that we used at Riverside was a goner when we disassembled the engine, and Phil and I decided then that we would either have to solve the problem or park the bike, since neither of us was charmed by the idea of continuously replacing used lousy gearbox parts with new lousy gearbox parts. We communicated the details of our situation to Tim Witham of S&W, and he put us in touch with the only man who could help: Mr. Marvin Webster.

You probably haven’t heard of Marvin Webster. He is a self-made millionaire who lives in Mill Valley, California and had more than some success in the electronics business. Like Tim, Web has been involved with Indianapolis race cars for some time as a sponsor, car owner, engine builder and tuner. Not only that; Web builds gears for Indy racers. When Tim told us that, we perked right up. We subsequently discovered that Web builds the gears for the off-road Baja Honda 350s, for off-road Baja Volkswagens, has done some work for Ken Roberts’ dirt-track Yamahas, has built gear boxes for Kawasaki’s factory-sponsored motocross racers and had some involvement with the six-speed Suzuki TR-750 road racers.

So we called Mr. Webster, explained our problem to him and shipped him the factory close-ratio Riverside transmission for his analysis. He called us as soon as he got it in the mail. “Nothing wrong with the design,” Web said. “It’s just that the material’s no good.” Could he duplicate the box for us using American gear steel? “Yes.”
shaftThe Riverside box was sent up in late October; we had a Webster transmission in our hands early in January, and after a modest amount of development work the transmission was ready to race. Web didn’t make a gear here and a shaft there, either; he made the whole thing, gears, shafts, splined washers and all.

While Webster was flogging the gearbox, Jerry Branch was working on the Ducati’s cylinder heads. Jerry knew that the top end’s biggest problem involved the inlet ports and the inlet valve. The valves measure, in a stock Super Sport, 40mm. Last year we ran 42s. This year Branch fitted 44mm inlet valves, again made from Harley-Davidson XR parts. Since there was no room in the combustion chamber for a 44mm inlet and a 38mm exhaust. Jerry simply made room by sinking both valves and then reshaping the combustion chamber to get the flow bench numbers up where he wanted them. After a lot of hours he produced a 7% increase in intake breathing.

As soon as Jerry was done with the heads I made a Lucite casting of the inside of one of the combustion chambers, machined it off right under the spark plug hole and sent it down to Venolia. “We need pistons shaped just like this,” we said. “Piece o’ cake,” said Venolia. Since we’ve been working with Venoila for two years they already had piston pin location, ring groove dimensions, valve clearance pocket shapes and deck heights worked out.

pistonpierres-workAnd while the gears were with Webster and the heads with Branch, our friend Pierre DesRoches went after the chassis. He removed all the business behind and below the engine that accommodated the center stand; welding in reinforcing tubes to stabilize the steering head just in case the bike might need it; re-assembled the Marzocchi front fork; welded up a beautiful little bracket to accept a Volkswagen oil filter mount; and fashioned a pair of exhaust pipes and megaphones which reflected discoveries made at the strip last summer.

As usual, everything came back at once; the transmission (“This thing is made out of the finest gear steel money can buy,” Web told us), the heads, the crankshaft (assembled by Rennsport Werke’s Jeff Bratton in Santa Clara,Calif.), the pistons.

Once we got it all together, our first stop, naturally, was Irwindale Drag Strip. If you recall, the Duck’s best numbers last year were 11.58 sec @118.89 mph with Daytona gearing. This year the ET dropped to 11.30 and trap speed climbed to 121.13 mph. We were especially pleased with the ET, since the bike was penalized by its new, ultra-tall first gear.

After the successful Irwindale outing Phil and I stopped by the dynamometer emporium of C. R. Axtell to find out how those drag strip numbers translated into horsepower numbers. The translation came out like this:

Torque HP
5500 rpm 55.67 lbs/ft 58.3 hp
6500 rpm 62.54 lbs/ft 77.4 hp
7500 rpm 57.84 lbs/ft 82.6 hp
8000 rpm 55.80 lbs/ft 85.0 hp
8300 rpm 57.20 lbs/ft 90.4 hp
8500 rpm 54.86 lbs/ft 88.8 hp

Beyond telling us that the Duck made a presentable amount of power and an admirable amount of torque, Ax’s dyno located the power peak, which was invaluable when we were setting the gearing for Daytona. We settled on 4.1743 overall, giving us just over 17.3 mph-per-thousand-rpm with a tire 76.6-in, in circumference, and a top speed of about 150 mph, not factoring in tire growth. The engine was still fresh after its afternoon on the dyno, so we went out to an AFM Ontario race for the final shakedown and got trimmed by Wes Cooley on Pops Yoshimura’s Kawasaki Z-1. Wes’s bike was handling well; we weren’t sure it would handle at Daytona, and we knew the Duck would.

It did, and Wes’s Z-1 didn’t, nor did Pridmore’s BMW, or Mike Baldwin’s Moto Guzzi, or John Bettencourt’s Z.

The Daytona Superbike field seemed split two ways: there were bikes that went fast and didn’t handle, and bikes that handled and didn’t go fast. The California Hot Rod went plenty fast (149.50 mph through the speed trap) and handled immaculately, despite a snapping cross-wind that came up just just before our race was flagged off and made the equipment of the honored opposition behave even more peculiarly than usual.

The rest of the weather didn’t hurt either. Because of Phil’s and my club racing background, when the Duck comes out the back of the truck it’s ready to race. Track-side R&D is not our idea of fun. But for many Eastern competitors, Daytona’s generous allocation of practice-time is crucial. When it rained Monday and again Thursday Phil and I were plenty happy. We didn’t need the additional track time; we knew the other guys did. We wanted to save the engine and save the rear tire — it was the only remaining D1750 Goodyear in captivity.

My race strategy was simple: a back-and-forth dice with Wes Cooley or David Emde, or both, was to be avoided at all costs. The Ducati’s advantage over the ultra-fast Z-1s came in the corners. But the finish line is on a straightaway, so in a “you’ve-got-the-straights-and-I’ve-got-the-turns” mix-up, I’d lose. I therefore wanted to clear out as quickly as I could and jam the Duck around the track at full honk for at least the first 10 laps before even looking back. On the ninth of 14 laps I felt my left knee touch the pavement in Turn One. Since that rarely happens I figured the time had come to check out what was going on behind, and ease up if further berserko riding was not called for.

Beyond the excitement of winning the one race I’ve been trying to win for three years, my biggest two thrills came later. The first happened when I met with the Ducati International Owners Club the next night at the Royal Scotchsman Motel in Daytona Beach and discovered that Phil and Gordon Jennings and Dale Boller and I weren’t the only Duck-freaks running around loose, and discovered as well that the Ducati’s Superbike win meant as much to the DIOC members as it did to us.

The second big thrill came 10 days later when we took the engine apart and found that the transmission, and every other part in the motor, was in perfect shape. There was a tattered shim here and carbonized oil there, of course, but compared to the post-Riverside tear-down the engine scarcely looked like it had been in a race at all.