Cycle News is a weekly magazine that covers all aspects of motorcycling including Supercross, Motocross and MotoGP as well as new motorcycles
Issue link: https://magazine.cyclenews.com/i/126268
third, a water-cooled Yamaha twin. On May I , again at Ontario but this time for an event sanctioned by Manning Racing/Continental Motosport Club (CMC). Philippe deLespinay - one of the three showed up with his beautiful, fast. water-cooled Yamaha TA125 . DeLesp ina y had a 300-foot lead before the first turn. He was too far ahead to be seen halfway through the race. Our MT125R stuffed its way into second place in an infield turn on the first lap, but four air-cooled TAI25 Yamahas shot past on the banking during the second lap. It took serious riding to get back into second place. and more serious riding to stay there . However. a minor practice crash had cut down drastically on practice time and prevented us from dialing in the jetting. (It had also convinced us that the slippery stock Dunlop KR73 triangular tires were not the hot tip.) Still, the bike turned lap times as fast as it took to- win th e weekend before. T he way we sa w it. t he bike needed more horsepower - a bunch more to be competitive.wit h deLespinay. O f course. nobody runs a "stock" road racer. Even Ya maha TZ750Ds. the " O W31 replicas" of professional racin g . do not remain sto ck. Pu m p ing in more horsepower is part of the road racing scene. Since, acco rding to H ish iki, the MTI25R has standard late-model Elsinore engine and exhaust system specifications, it is reasonable to say that much more power is attainable. Countless motocross tuners sell speed parts for Elsinores, and the right combination could do wonders for the MTI25R . We may never know if an FMF or DG or Ron Pierce Enterprises or Mack Kambayashi MT125R could be the next " Killer DKW" of California club racing. (Killer DKW won 32 straight 125cc Production road races and both the ' AFM and CMC .c lass championships in 1975.) According to American Honda representatives . the MT125R is fast enough - stock - for a beginner to win on "if correctly tuned ." Thus , said the Honda men, there was no need to modify our MTI25R . One rep put it this way: " If technique is good . should win ." So, we didn't receive permission from Honda to modify the bike. We decided to give it one more shot anyway. at Riverside on May 22. First, the MTI25R went back to the Engineering Department at Honda, where Hishiki certified it mechanically sound. Before heading for the racetrack . we replaced the stock tires with Michelin 2.50 /18 front and 2.75 /18 rear M38 PZ2 tires from The Cycle Tire Distributor. 1333 Redondo Ave .. Long Beach. ' CA 90804. We chose Michelins because: I) we had been impressed with the performance of Michelins on larger bikes that we had raced : 2) photos sent to us from European 125cc World Championship road races showed the same design Michelins on the winning bikes: and 3) Michelins were easily available. where our first choice, (the Yokohamas used by American Honda on the MT125 R that won the 125cc Amateur race at the Charlotte. North Ca rolina national road race in March), were not available. Mo unt ing the wider-profile Michelins required the re moval of the front fender a nd th e relocation of t he rea r ex haust system mo unt. At Riverside on race d ay. not only had deLespinay brought out his watercooler. but Doug Draper and Bill Brinckerhoff had entered their aircoo led Yamahas. Judging by races earlier in the year . any of the three could win . In addition. Cook Nei lson of Cycle and j od y Nicholas (who had won at Sears Point on May 15. beating Draper) of Motorcyclist were entered on MT125R test bikes. Cycl e hangeron and test rider Mark Homchick had entered a basically -stock TA 125 Yamaha - which-wouldn't have been noteworthy except thatHornchick is a gifted natural rider who do-es magic with motorcycles and doesn't weigh much . either. It was shaping up to be a real race. In practice, we discovered that fast MT125Rs do exist. Ours was not one ofthem . j etted and geared identically to the MT125Rs of Neilson a nd Nicholas, our MT125R was a po rker - wouldn't pull sixth gear on th e straightaway, wouldn't accelerate hard. wo'!ldn't get out of its own way. O u r MT125 R passed other 125s one way - by stuffing under them at turn entrances. O u r bike seized in the race, whi le running a bo ut sixth. a long ways , be hi nd, with its hands,fu ll staving off the repeated straightaway. passes of an air-cooled TA125 . Ho mchick won the race on sheer talent, with Neilson on a MTI25R second. Dra per third. deLespinay fo urth and B ri n ck e r h off fifth . Nicholas crashed. Neilson had changed the stock tires for the only set of Yokohamas available in the country, while Nicholas ran ' Fren ch -m a de Dunlop K81s like those preferred by deLespinay. Homchick won on the Dunlop KR73s Neilson had taken off the MTI25R . Switching bikes and entering the 100 GP race for testing only . Homchick and Neilson found that the Honda. with Homchick aboard . was about five seconds a lap faster than the Yamaha with Neilson aboard . In the 125 GP race. Homchick on the Yamaha had been almost evenly matched with Neilson on the Honda . Our test rid~r had shifted our bike at the Hishiki -specified -red line of 10,500 r.p.m . throughout the test. According to Neilson . he shifted at 12,000 r.p.m. ; ran Castrol R bean oil at 20: I instead of the Hishiki recommended Honda Injector Oi l (which smells sus picious ly like Pennzoil two -stroke oil) at 40 : I : and backed off the ignition timing lead from the manual -specified 2 .3mm before top dead center (BTDC) to an actual 1.9mm to avoid detonation . Nicholas told us that he also ran Castrol R 20: 1 in his MT125R , but left the ignition timing a t 2.3mm BTDC with no ill effects. We have seen Honda MT125Rs capable of taking on all comers and winning on the road racing circuits of California. We haven't ridden one. though . Tuned and set -up "t o American Honda's specifications -by American Honda 's project engineer. our MTI25R would not take on all comers, and would go fast enough to run with the most competitive 125s now being campaigned in California. We reject any theory that the machine was not ridden correctly . since straightaway speed has little to do with rider skill - anybo-dy can twist the throttle - and since the test rider is an experienced road ra cer with many club-race victories to his credit. Our test MTI25 R was a toad. In spite of techniq ue, it wou ld not win : • Specifications Engine type .• air-cooled. seven-port. two stroke Carburetion _ 34mm Mikuni Ignition COl Claimed horsepower 25@ 10.500 Claimed weight, dry 154 Ibs. TIres, front & rear Dunlop K~ 2.50X18 Sug gested retail base price ... •.. •.•• .. $1,764 You can't ju st buy an MT125R, take it to a race, and win. The machine needs careful preparation and tuning by a knowledgeable peI'8Ol"I to be competitive. Phil Schilling spent two fu ll days meticulously preparing Cook Neil'-on's MT125R. Neilson's bike was fast. Our bike (shown abovel wasn't. Does the average road racer have a tuner like Schilling avallable7 can pr!vately-owned MT12SRs win, or will it'take experts lik e Neilson and Jody Nicholas to take the Hondas to victory7 • ' en z ~ w g >CD ~ ~ L ""':' --==_---J Fuel tank . . . • . . . • • • ... . . . 303.69 Expansion chamber.••• .• 242.60 Transmission . • • • • • . . . • • 727.44 Tachometer••••.. . • ...•• 180.20 Rear wheel ri m assembly. 168.50 Rear tire •• ••• ..•••• •••••• 60.40 Rear tube ••• .•••...•...•• 20.40 Front tire . . • . • • • . . • • . • • .• 60.60 Anybody w ho buys a Hon da Front wheel rim .•••••..• . 85.00 MT125R is in for a shock when the Rear wheel rim •••.•.•.• .• 85.00 tim e com es to purchase Swingarm •.•••....... .• 145.60 replacement parts. The little road Clip ons (barsl . . • . . . . . . . . _ 60.60 racer is actually built by Honda - Front fender . . .. .. .. .. . . • 30.30 Racing Service Corporation, the Fairing lens (bubblel••••• .. 90.50 racing arm of Honda in .Japan, W ith Fairing ... : . . . . . . • .. .... 260 .66 only 200 of the bikes offered for Front fairing stay • .•• ... .. 42.50 " 86.50 sale in the United States, it isn't Seat surprising that the machines are Rear fender •• .. . .•• •••••• 42.50 14.60 expensive (suggested retei l is Spark plug $1,764, plus shipping and set up). It is interesting to note that a Even tak ing th e li mi t ed complete TZ250 Yamaha fairing prod uction int o accou nt. parts offered by a . leadi ng fair ing prices are incredible. The followi ng manufactuer sells for less than examples were selected from .tne $150. Mack Kambayashi, a noted official American Honda retail parts road,racing tuner, charges $125 for price list supplied to Cycle Ne ws by a custom-bui lt exhaust pipe . Larry Shultz. ,Service Manager of Compared to the quoted Honda Cycle Center Stores II. a Honda price of $242.60 for a standard shop in Fremont, Ca if. l exhaust pipe, Kameayashi's price Cylinder .._ ..••• .•••. .. • 1n.3O - wh ich he thinks is the highest in • Carburetor. . ...• . .••• .•• 1~80 the country - looks like a bargain. Parts prices make MT12sR ' a rich-man's toy 43