Tul-Aris prototype studio view When Ex-Astrophysicist Robin Tuluie set out to build this remarkable “fusion motorcycle” (made of elements from snowmobiles, motorcycles, and F1), the Grand Prix bike racing that began in 1949 and became 100 percent two-stroke dominated in the 1970s, was about to become the all-four-stroke MotoGP. The dominant aspect of two-stroke 500 GP racing had been super acceleration, resulting from the union of the explosive two-stroke powerband and very light weight. The minimum came in the early 1980s, a Suzuki weighing 115 kg (253 lb.), but was later increased by rule to 130 kg (286 lb.). Because two-strokes depend for their remarkable power on acoustic resonances, their power is narrow, a “one-note samba” broadened only by such arcane means as injecting water into the exhaust and varying the heights of the exhaust ports. Power peaked just short of 200 hp, later being reduced by the switch to unleaded fuels (“lamp oil”) that required lowered compression ratios. The Tul-Aris was definitely up there in 500 territory with its 264 lb. (120 kg) weight and 165 hp. And it was constructed not by a mighty corporation, but by a band of like-minded enthusiasts. Seen in retrospect, two-stroke racing was a mistake, equivalent to trying to blow the riders off the corners with dynamite. Good acceleration! The need to remove the sharp edges and other “singularities” from two-stroke power brought the first electronic torque-limiting systems into being in 1990. The challenge of providing chassis, suspension, and tires capable of surviving two-stroke power forced the modern motorcycle into being; when four-stroke MotoGP began in 2002, usable solutions to most problems were at hand, in off-the-shelf form. 500 lap times improved little after 1992. I know that it’s fashionable today to assert that racing is about competition, not lap times. But I can assure you that racers and their teams are always and most definitely thinking about lap time because that’s what wins races. If your team “competes well” (whatever that means) but your lap times are rubbish, team sponsors fall away and rider contracts are not renewed. Therefore it was heartening to see lap times dropping rapidly once more as MotoGP began. New possibilities! Compared with 500s, MotoGP bikes weigh a ton (last season’s minimum weight was 158 kg., or 348 lb.), but what four-strokes brought to the table was not so much killer power-to-weight but smoother, more usable power that could be fed in rather than detonated. 500 riders had to  wait to apply power until the bike was half-upright, then see the thing snap sideways on-throttle in a series of slip-and-grip near-highsides. But the smoother power application possible with four-strokes allowed them to be ridden closer to a corner-speed style. But the mind is always asking questions, even when we’re sleeping. What if, it wants to know. What if the full range of electronic rider aids were applied to imaginary 500 GP bikes of an imaginary future? What if the smoke and heavy fuel consumption of the traditional carbureted two-stroke were replaced by low-emissions direct fuel injection, as now used on modern two-stroke snowmobiles? Unless Bill Gates or Warren Buffet becomes fascinated by this question, we can’t know. Robin Tuluie began to apply formal dynamic analysis to the motorcycle as he was building Tul-aris, but before he could progress far, he was summoned into Formula One. Like the late John Britten, he wants answers based on fundamental principles–not a collection of empirical hocus-pocus. That he has been effective in F1 is attested by the banning of some of his concepts; in the modern new-rule-a-week world of the racing business, anything that really works well is promptly banned as “destabilizing.” Fundamentally, in our brave-new world, trying to win is destabilizing. Therefore having one’s ideas banned is praise indeed. Tul-Aris is a lovely creation, a clear statement of the single-mindedness of the two-stroke era. We wonder what sort of motorbike Robin Tuluie might create now, given the opportunity.

This article, Since Tul-Aris, first appeared on Cycle World.

Related Articles

About Author