The Honda Super Duper Hawk
WHEN Eric Dahlstrom won outright the November 8th 350cc road race at Southern California's Willow Springs Raceway and was beaten in the 500cc event only by a trio of well-prepared Norton Manxes, his triumph was one of double importance.
For Dahlstrom, a 6-foot 2-inch, 20year-old rider from Sausalito, Calif., the years of riding on the twisty Coast Highway near his home town and 12 previous AFM events had paid off in a really impressive personal performance in this pair of races. For owners-tuners James Kibblewhite and Gerald Young, some expert modifying of a stock Honda 305 Hawk had developed an astonishing instrument of speed, as was proved by the events of the day.
Kibblewhite and Young are co-owners of Precision Machining, a firm headquartered in a small but well-equipped shop in Pacifica, Calif. Here, the partners in speed have developed their line of PM speed kits for Hondas, and here they continue to experiment, using their remarkably quick racing machine as a test platform.
Though Kibblewhite and Young work closely and well together, they are personally contrasting individuals. "Kibble," as his friends tag him, is quiet and serious, and speaks with the assurance of one who is competent in his field. A mechanic by trade, "Jerry" Young is more extroverted. He is the quicker to smile, and his round face sports the optimism of a man who has created a winner.
Young and Kibblewhite first met several years ago. Mutual interest in cycles ("we had both been exposed during our teens," Young says, led to a continuing acquaintanceship and later they converted Kibblewhite's Norton street bike to a dirt track machine.
"The tracking lasted about one season," Young remembers, "and then some of my pre-army dragging enthusiasm rubbed off on Jim and he decided to further convert the Norton to a dragster." While Kibblewhite was engaged in dragging, Young sponsored a dirt machine on his own, but the friendship continued.
"Probably why we got together as we are now is that I would come here for machine work, and Jim and I would swap ideas — he on his dragster and I on my machine — and it just led to a closer association."
The "closer association" became Precision Machining (PM for short) which now offers a 350cc conversion kit for the Honda Hawk, and an oversize valve installation for the same machine, in addition to other speed items now on sale and several being developed.
As the business grew, so did the itch to race. As Young says, "We were preparing racing machines for several people, and our relationship working with them kind of inspired us to get into it ourselves. We wanted to bring some of our own ideas into play."
Building the super-quick 350 Honda was a painstaking job completed just in time for the June AFM road race at Vacaville. Quick victory, however, was not to be; a defective tensioner on the camshaft driving chain ("that's our story, not Honda's," Kibblewhite says ruefully) brought on a case of erratic valve timing and the machine was retired.
Things went better at nearby Cotati on August 16. Dahlstrom had troubles at the start and spent a frustrating 30 seconds after everyone else had started, trying to get off the grid. Once underway, however, Dahlstrom and his mount really went to town and had worked their way into the lead when the young pilot lost it in a switchback and crashed with only one lap to go. Pulling the bike back into action, Dahlstrom watched four riders go by as he mounted and sped off in hot pursuit, catching two to qualify for third place.
The next outing, at Cotati also, came up October 4 and found a new set of cams in the machine. The new cams were another experiment, less radical than the first, but they worked to perfection and Dahlstrom was just stalking the first place man when the leader's engine blew, giving Eric the lead and then the win.
The stage was then set for Willow Springs. Wildly revving and clutch slipping to get the high-geared Honda off the line, Dahlstrom was third at the start, then got up on the cam and passed Larry Grossman's Honda on the second lap and Ron Grant's potent Parilla on the third.
"It was going smoothly," Dahlstrom says. "I did a 1:45 lap (86 mph average) but then they put out the big sign telling me to slow down, so I dropped to 1:47 and won."
Twenty-five minutes after the 350 finish, Dahlstrom wheeled the still-hot cycle onto the starting line for the 100mile open class race and worked his way up to finish 4th behind Vic Vila.
The performance of Dahlstrom and the Honda were impressive from several angles. His 1:10 win over Parilla-mounted Ron Grant is believed by Dick Kilgroe, head of Custom Plastics and distributor of PM kits, to be the most Grant's machine has ever been headed. And Eric's lap times were low and consistent, only varying two seconds — between 1:45 and 1:47 — where the track record is 1:43, jointly held by three of the country's fastest Nortons.
Dahlstrom's reaction to his machine is quite favorable, though he also mentions a drawback.
"The machine apparently has superior handling to other Hondas," Eric feels, "although this will be argued by others. Going through that big sweeper (turn 8) at Willow it didn't waver or sink; it didn't deviate at all. I can hold it flat out on that stretch, where the Manxes have to turn off to get into the corner."
THE HONDA SUPER DUPER HAWK
GEORGE MARTIN
The machine's Achilles heel is stopping. At Cotati, where the course is twisty and the turns are tight, the twin leading shoe Honda brakes overheat and fade. At the second Cotati event, Dahlstrom says he rode nearly brakeless, yet the bike's lap times were Vi -second faster than those of Honda-mounted Larry Grossman.
"We've gotten so much horsepower out of these machines that we haven't found a drum brake that will stop it," offers Kilgroe. A disc brake, the obvious answer, is being developed by C & T Alloy of Hayward, and it should be an interesting unit. The idea is to make twin discs, each smaller than the usual unit, to avoid a pull to the right effect to which motorcycle discs are prone. Each disc would "float," so as the inboard (and stationary) caliper pad wears, the disc will not have to bend when the pressure is clamped on. The wheel hub will be magnesium.
Back on the plus side we have the Sausalito rider's opinion that the bike can be geared still higher. "It could pull one tooth less on the rear sprocket," he believes. "It peaks in all gears (9,400 rpm) and won't go above 10 grand without really straining.
"Going downhill at Willow Springs it turned 10,200. It kind of surprised me, it was running so well near the end of the 500cc race. It must have been loosening up or something, but it ran faster.
"The power comes in just over 7,000 rpm," Dahlstrom adds, "but I never drop down that low anyhow so I don't pay much attention."
A front-to-rear guided tour of the machine reveals a great many differences from the stock Hawk. Cerriani front forks from Italy ("the heavy models") were adapted, and the rear suspension mounts were changed from a plate to a yoke to accept rear shocks made by the same firm. In the swinging arm, bronze bushings replaced the stock (composition) units.
Magnesium hubs from an early Honda works racer are fitted front and rear, saving seven pounds on the unsprung weight. The rear hub is narrower than the regular part, so it was adapted with spacers to fit the swinging arm by Slim Kokker, of San Jose. Avon cling-rubber racing models are the tires used (2.75/19 front, 3.25/18 in the rear), and the tank, seat and fairing are all custom made by Custom Plastics.
The racing seat contains a 1 Vi gallon gas tank connected by hose to the main tank. Though it augments the regular fuel supply nicely, it adds about 12 pounds to the rear of the bike, which makes it "a little heavy in the tail."
A hydraulic steering damper from a scrambler model is installed, and aluminum alloy is used for pegs and fairing brackets for lightness.
Inside the engine Kibblewhite and Young have worked many wonders. First, of course, was installation of their 350cc conversion pistons, which increase the bore to 64 millimeters, while retaining the 54mm stroke. The standard crankshaft was lightened by machining the flywheels, and the head was "reworked considerably," in Kibblewhite's words, and a PM oversize valve kit installed.
Using welding, the head was modified to take a pair of l^-inch Amal GP carburetors with remote float bowls, and the inside of the head was smoothed and polished for best gas flow. The cams are experimental at this time, but production is planned soon.
The clutch is a Barnett unit with PM racing clutch spring kit installed. The plates are alloy, with friction material made of powdered cork and neoprene. Kibblewhite says no slippage has been experienced.
An extremely close-ratio transmission was obtained from James Dunne at Dunnel Products, 26 Albermarle Ave., Pottersbar, Middlesex, England. The gear sets are rare, for Dunne will only produce them in lots of 10 now and they are by no means an easy fit. They cost $140.00.
Among other difficulties, the input gear for "second" is so large you have to mill out the shifting fork, thin it away, and then slice a section from the bolt that holds the shifting fork to the shifting drum, so it will clear the whirling gear. The engine's compression ratio is 9:1, and the final drive ratio is 5.53:1.
Kibblewhite did quite a bit of work to improve crankcase breathing, installing two huge breather hoses (resembling the one Harley-Davidson uses on their Sprint scrambler), from two parts of the engine. A large, conical-baffled breather is mounted on the engine plate above the transmission area, and another hose emanates from a Honda scrambler dipstick tube just aft of the cylinder barrel. Both breather tubes have remained quite clean, and Kibblewhite says oil consumption has been negligible. For the economy-minded, by the way, the bike gets 28 mpg.
Future plans include an AMA competition license for Dahlstrom, so he can ride at Daytona in March (He got an Expert card. Ed.), and a new hopped up Honda track machine.
Meanwhile, that glow over Pacifica is from the lights burning late at 275 Kent Road. •
