Cycle News - Archive Issues - 1970's

tri als , brought his 175cc Penton/KTM , The drag strip portion of th e test was hel d th e first d a y. Riders were instruc ted to be sure th eir bikes were je tted as well as possibl e before th ey began th eir runs with original ca rb u re to rs. To do away with a ny va ria b les ca used by in consistent sta rts. rid ers would go th rou gh th e lights on a roll in g sta n . usu a lly in second gear. All tha t was asked was th at th ey be co nsis te nt each tim e. not experiment ing with di ffe re nt shifting techniques.. After practi ce ru ns to be su re th eir bikes were wa rmed u p a nd to ga in co nsiste n ey. the rid er s eac h m ade two tim ed ru ns with th eir origi na l carbs for record ing . From th er e th ey went to th e pits to replace th eir ori gin al ca rbs with Lectrons. In most cases th e ins ta llation of th e Lectron was a quick bolt -on repl a cem ent. Only th e Penton /KTMs with th eir co m p lica ted frame and airbox d esign required tim e to make th e c ha nge over. . We were som ewh a t appreh ensive th at th e Lectron s wou ld not receive a fa ir shake in the test . becau se no ne of th e rid ers ac tua lly kn ew how to fine tune the metering rod system . The Lectron representatives just gav e th em ca rbs with the met ering rods close to what th ey th ou ght wou ld work for each particul ar bik e . Only one of the bikes received a cha nge in rods after it was test ed with th e Lectron installed . Everyone went ba ck to th e drag strip. th is time to mak e four runs with th e Leetrans. Amazin gly. every bik e sho wed lower acceleration times . usu all y by a n average of 1/ 3 a second . Most impressive was th e Husky Automatic which not only turned th e fast est tim es all d ay , but proved to be th e most consiste nt because it shifted on its own . Despite the fa ct th at none of th e Lectron ca rbs wer e fin e tuned . every b ike proved faster. After th e drag strip test, some of the rid ers went out to play in a nearby wooded ection . Ea ch returned highly impressed wit h the performance of the Lec tro n , Bo Bobb it had a gri n .from ear to ear. " It' s amaz ing. I spe nt days ge tt ing th e Bing on y 370 Pursa ng je tted to where I th ou gh t it was perfect , th en I just bo lt on th is Leetron and the b ike is better. It feels faster on top-end . I ca n let it id le down as low as I want in th e woods and it won't load u p . I can la y the b ike down on its sid e and it till id les ." . Even more amazing was the fact that on a pipey bike like Jeff Hi ll's 250 cc Penon / KT M the Lec tron had smoot hed out the powcrband and caused th e b ike to ose its pipe y feeling. The b ike co uld be lugged d own to idl e speeds in third and ou rt h gear. a nd then cleanly accelerated away without a ny sign of bogging or oading up_ The Lectrons had a ctua lly changed the power cha rac te ristics of th e ngines . though it hardly see me d possible. The seco nd day of testing took pla ce out at Burnt Hi ckory motocross track . iders wer e timed throughout th e da y as they turned laps with their regu la r ca rureters and th e Lectrons . Accuracy wise , trying to ta ke co nsistent tim es on th e ot ocross track became im poss ib le. No matter wh ich ca rb u reto r a rid er was usin g , is lap tim es would bec ome progressivel y qui cker as he learned the tra ck and found uicker lin es. This would happen up to a point whe re th e rid er would grow tired nd his lap tim es would show. Also. track conditions cha nge d during the day wh ich ffected tim es. as d id th e half hour or so a rid er rest ed whil e he cha nged caruretors on his bike. We wer e roughl y able to determine th ou gh. that at Burnt ickory where the riders were turning lap times in the area of I minute. a nd 18 econds, lap tim es with the Lectron carbu ret or s wer e lower th an th e stock caruret ers a nywhe re from 1-3 seconds depending on th e rid ers . The faster th ree econd improvements were cr edited to t he better high -speed rid er s like Brad a lla ce and Jeff Hill. Brad W a lla ce .. "The stock power on an R M 370 is either on or off. The Lectron moothed out th e powerba nd to wher e it would ce rta inly be a grea t advantage on a ight tra ck . The stoc k Suzuk i ca rb ha s no provision to id le with th e th rottl e off. T he ectron does id le. especi a lly when you fall, whi ch has to be an import ant advantage n a b ike like th e RM 370 whi ch doesn 't ha ve a primary kick sta rte r ." ' J ef f Hill -- " Ii works really smooth, and beca use of thi s a Lectron might not feel ' st to a motocross rider who likes th e seat of the pa nts kick he would norm a lly get ithou t it. The tra il rider will rea lly not ice the difference. After ru nning slow or ' gging the Lect ron will acce lerate awa y cleanly, wh ile a Bing ca rb uretor won 't. " ' H owa rd Gilliam .. "T he jett ing seem ed more precise, sm oot her with the Lectron , y Automati c picked up more low-end a nd mid -range respons e. My Bin g was ia led -in as close as possibl e and th e Lectron just ou t-performe d it. " Frank Lamb -- "T he Lectr on smoothed out rou gh ed ges and helped the power. I . uld rea lly not ice th e difference going up hills." rapping up . c1 . Other adv antages of th e Leer ron a re better fu e l econ omy. especiall y with reed lve engines. less susceptibi lity to a ir pressure and a ltit ude cha nges because of t he are constant vac u um the metering rod creat es, a nd th e clea r pl asti c float bow l akes it ea sy to see if t he Lectron is ge tt ing gas a nd if th e howl con ta ins a ny d irt or =t ~ - • air Intake ,.... ~ ~ ... float bow l METERING ROD OPERATION - , ....... - - ... - - - - . The Lectron ca rbure to r out· performed every other carburetor on each of th e ikes tested , d oing so with some pretty am azing results, especia lly a t low rpm where igh · perform a nce two-strokes a re n't expected to run well . Why our tests proved the Le ctron to work so well , and Dirt Bike's test didn't , m ay e due to the foll owing rea son s. First is th at a .dyno test is a sta tic me asurement of J rsepower at certain throttle sett ings. Great for horsepower measu rem ent at a par· cular rpm . but it d oes nothing to det erm ine how a ca rb u retor performs under rying engine loads with a constantly mov ing throttle . > he Lectron 's flat -sided met er ing rod creates a much d ifferent vac uu m than a T ~md needle for drawing fu el up out of th e float bowl ac cording to a ir flow past th e edl e. The flat -sid ed Lectron metering rod requires mor e vac u um to draw up el,' so it doesn't h ave th e ten cencv to produce a n overly rich mixture wh en th e id e is opene d qu ickl y for fast acclera tion. Short of a n eng ine-d riven pump like on I injection systems which feeds the right amount of gas a cco rding to rpm . th e ect ro n ca rbu re to r is m or e se nsitive to t he speeds whi ch th e throttle is ope ned a nd e am ount of ai r flowing by th e metering rod . For exa m p le. when th e Lectron's de is snapped o pen quickl y at low rpms, t he slow a ir flow past th e metering ro d 't sucking up as mu ch fu el a ll of a sudd en as a taper ed needl e would produce 'c ause th e Lcctron 's met ering ro d is still offering th e sa me profil e to th e in coming r. Only when engi ne rpm inc reases d oes vacuum in cr ea se eno ugh to d raw mo re tcr, CUTAWAY OF MAIN BODY Idle & low rpm range functions as: mid-range high rpm pilot Jet needle Jet & need le main Jet 1/8 MILE ACCELERATION TEST stoc k ca rb How ard Gill iam 360cc Huskv Automati c Bo Bobbitt 370cc Bu ltaco Pursanz Brad Walla ce 370cc R M Suzuki J eff Hill 250cc Penton /KTM MC5 Howa rd Gillam 360cc YZ Frank Lam b 175cc Penton / KTM MC5 Lectron ca rb 7.99 8.05 7.67 7.61 7.71 7.72 8. 168.14 7.96 8.01 7.97 7.94 8 .33 8 .2 1 8 .09 8 .29 8. 11 8.30 8.40 8. 54 8_26 8 .19 8.26 8.03 8 .63 8.47 8 .32 8.34 8 .30 8. 15 8.74 8 .87 8.75 8 .77 8 .77 8.66 . Penton 's Don Rose ne said th e p urpose of the test was to dete rm ine if th e Lectr on rbure tor wou ld be a worthwhile im p roveme nt for the own er of a ny din b ike , ieci all y if he wanted th e most im pro veme nt for th e leas t a mo u nt of money. It finitely was proven . a long with thefa ct t ha t it's probab ly the only performa nce di ficat ion you ca n m ake to a n eng ine without harmi ng rel iab ility. Not e: T imes are on ly useful for dete mining indi vid ua l im p rovement s with ca rbur etor ch anges. Bikes wer e no t geared for opti mum accelera tion a nd each rider used the sta rt ing tech nique he liked best. • 13

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