Cycle News - Archive Issues - 1980's

cally made and recorded by the SuperFlo dyno is the engine's Brake Spe" cific Fuel Consumption (spec-fuel). This is a direct measure of how efficiently the engine is burning fuel. If a restrictor were to upset how well any critical engine tuning factor worked, it would show as a richer running mixture (higher spec-fuel). Except at 29mm where the mIxtures richened slightly, none of the restrictors significantly affected how well these highly tuned engines worked. The restrictors merely reduced their power output, especially near red line where good breathing is most important. A stock Honda reaches maximum power output at about 9000 rpm. With a 32mm restrictor it is through at just over 8000 rpm and its peak power is in the low mid 80s. Similar results were obtained with the Gardner Harley. Scott' state of the an 107 hp Honda and Parker's superb 100 hp Harley (tuned by Bill Werner) were affected more by any given restrictor size than the other two. That is simply because these engines gained most of their original power advantage through better intake (and exhaust) air £low. A flow reduction in the very best engines will have a greater proportional effect on them than it will on an engine with more modest air flow. Still, though, the best engines will remain the best engines. A given se~ of restrictors might pull, say, seven horsepower off the top of a stock (92 hpj Honda; the same set might take 12 off Scott's 107 hp overdog. So, one loses seven and has 85 to work with, the other will lose 12 but still has 95 with which to do battle. The best one remains best but isn't as much better as it was Dollar figures are totals tor the year. before getting the restrictors. Restrictors should close-up the field a bit. There are many tuners who believe that restrictors will demand new cams, different sized carbs, exhaust and intake lengths. Considerable testing by Jerry Branch has shown that this is not the case. If a 40mm carburetor works best on your engine the WilY it is tuned now, it will continue to work best with restrictors in place. The only changes likely to "be needed to run restricted engines will be different gearing and maybe different main jets. While inlet restrictors may well reduce maintenance costs and, therefore, the total cost of racing, they are not a long term solution to some of the problems facing dirt track racing. The AMA' own spectator statistics seem to indicate that people would rather pay to watch motorcycles race that are similar to what they can actually buy and ride themselves. In the most popular road racing events, Superbike and Battle, of The Twins, the motorcycles are at least based on production motorcycles. A look at the near past will show that this has been a pattern in road racing; the closer the competitive machinery resembles what the fans ride, the more popular racing them has been. A din track racer that staned life as a production motorcycle will certainly be more interesting to an American spectator than an unobtainable, one-off factory special. Pro Stock drag racing is very popular. The machinery is expensive to build and operate but there is no shortage of participants, indeed, one of the current problems in drag racingis what to do about the hugenumbers of competitors who arrive to do battle with the likes of Terry Vance (Left to right) Kevin Cameron. Jerry Branch and Bill Boyce discuss the results of the day's test session. and Jesse Gatlin. A Pro Stock drag racer costs about $25,000 to build and maybe halE of that to race for a season (about a dozen races). VHR builds roughly 100 engines for its customers each year at a cost of $9950 each, not counting the original cost of the engine. Clearly costly racing can be popular. Drag racing is popular because it is just that: popular. The only difference between a spectatoranda racer is dedication and money. If you really wantted to, and could find the money, you could run your Pro Stocker against Terry Vance's. You could stan with the Suzuki GSl150 you rode to the race on. There is a direct link between what you, as a spectator, buy to ride on the street and what Terry • Vance races. A drag race fan is much closer to participating than the dirt track spectator can ever be. NASCAR racing is enomiously successful. Motorcycle Pro Stock drag racing is, on a lesser scale, very successful. Both are profile classes; the machinery looks like what the fans ride or drive to the even t. Noone attending an AMA National flat track event is going to have any illusions about being able to ride what they see being raced. The time is long past when one could sit in the stands and root for a Gold Star or Harley 45incher and then go out to the parking lot and ride one home. While intake restrictors will probably help ease the cost of dirt track racing for those who are still in it, it is unlikely that they will fill the stands. An 85 hp unobtainable motorcycle is no more magnetic than one that has 95. • ALWAYS WEAR A HELMEr A..~D EYE PROTECTION. Program lIubject to change wlthoutnoti~. Standings and wlnnln~subject LO confirmation. Interceptor is. Honda trademark. 01986 A.merlcan Kondl MotlirCo.. Inc. (11/86).

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