Cycle News - Archive Issues - 1980's

Scott Parker. Jay Springsteen and Chris Carr tested a prototype. perimeter- design dirt track frame in California the day after t he Sacramento M ile. Parker powers Harley-Davidson's prototype chassis through turn one on the mile ova l at Cal Expo State Fairgrounds in Sacramento. Harley tests new dirt track frame By Farren Williams Photos by Mitch Friedman SACRAMENTO, CA, AP R. 17 ' Harley-Davidson factory riders Sco tt P arker a n d Chris Carr, and three-time Gran d Na tional Champion Jay Sp ringsteen , tested a prototype XR 750 dirt track fram e today on the m ile ova l a t Cal Ex po Sta te Fairgrou n ds. . 20 After a full da y o f tesung, th e riders said th e new, one- of-a kind " chassis is. a t least as goc!d as Har ley s ~ toc k d irt track c h.a ~s l s . H a r ley-Davidson raCing offic ia ls added that th ey are pleased wi th th e results of th e testin g. The protot ype i s a r igid, perimeter- st ye fram e designed to red uce flex. Perimeter design features two, thick, rectangular, upper frame tubes running straigh t from th e steering head to th e swi n~rm pivot, wrapping around th e Sides of th e e ngi ne. H arley-Da vidson 's s tock chass is features convent ional twin downtubes wh ich run under th e engine. Perimeter fram es are co mmon on roa d race bik es, and the new H a rleyDavi dson unit is sim ilar in ap peara nce to ·the Delta Box aluminum frames found o n Yamaha 's top-ofthe-line , FZ-seri es sport bikes. The H arl ey chassis, how ever, is mad e from folded and formed 64130 sh eet chrome mo ly steel. The fram e features single shock rear sus pe n sio n with th e sh oc k mounted o n th e left side of th e bike, but it ca n be changed to dual rea r shocks, if a rid er o r mech anic so desires. Parker's tuner, Bill Werner, currentl y fa vors th e single sh ock setu p. . The frame is wrapped around a factory H arley-D avidson XR750 engine which Parker described as, " a dyno engine, but nothing sp ecial. " " The new frame is just a little bit more rigid," Parker said before th e test. " It's never been on the dirt _ before, so we'll just see how it goes ." After the test , Parker said the new chassis is, wel l.id ifferen t. "It's not like th e Lawwill fram e we'v e been riding, " said Parker. " Yo u seem to have a little more trouble keep ing your foot on th e peg iii the corners. " It do es feel more stable," ,Parker sai d. " It feels a tad bi t top heavy and the front end feels a littl e different - it isn 't go od, it isn't bad , it's j ust different. That made me a bit more ca utious wh en I was riding it. " It feels twice as wid e as a H arl ey," said Parker. " When you let off th e gas a li ttle, she wa nts to co me back ' a nd tra ck, and that 's ~ood . But when you hit a slick spot 111 a corner a nd it went sideways, it went comp letely sideways a nd it di d it rig ht now. " It 's definitely got potential but we need more tra ck time." For th e-most part, Carr agreed wi th his teammate. _ "It felt a little top-heavy," Carr said. " It handled well. It tracked through the corners. I could make the thing go wh ere I wanted it to go. It cou ld definitely be something in H arl ey-Dav idson 's future. . " I turned my fastest tim es of the day on that motorcycle," Carr said. " It's harder to rid e through th e corn ers. I had to muscle it a little more and use a little more throttle cont ro l to keep the wh eels in line." According to Rob North, the Chula Vista, California, fabri cator wh o design ed and built th e frame , the concep t behind th e chassis is to, " ma ke th e fram e more rigid; to stop the wobbling a nd flexing of the rear wh eel. " It ha s the sa me geometry (as Harley-Davidson's stock chassis) but it has a different look and, because it's a perimeter frame, it 's more rigid. Englishman North, who came to the United States in 1973 and " never went back" is rem embered by most race fans as th e fabricator who designed and built the road race frames for the Triumph triples a nd three-cylinder BSAs ridden by Dick Mann and his contemporaries on the National circu it in th e earl y 1970s. According to Harley-Davidson Race Team Manager Bob Conway, th e perimeter fram e passed it's first test with flying co lors. " We had three questi ons wh en we went testing," said Conway. " Is it safe? Yes, it is. Is it as good as what we have now? Yes, it is. Will it respond to cha nges th e way we want it too ? Yes, it will. Now all we need is tim e and money to ma ke more modifications. " I ca n 't com ment on th e (la p) times," said Conwa y. " A lot of things affect tim es, like track condition s. T he track keep s cha nging during th e day. I wouldn 't swear on a stack of bibles that it made them (the test (Co nti nued to pag e 25)

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