The ELF V4 500. Scary

It may have been nearly 200bhp and needed extra weight adding to get up to the 130kg minimum, but the Elf 500 was born of sidecar tech. Kind of.

It stood alone as a particular monster at the time, one of the most difficult motorcycles there has ever been to go fast on. Forward thinking engineering or a huge blip in the long history of 500GP bikes?

The heart of any motorcycle is its engine, but all the more so in the case of the Elf 500, whose wide-angle Swissauto V4 motor gave rise to the whole bike’s creation. Yet, while the engine appeared at a cursory glance to follow the conventional Made in Japan route, it was far from effectively being a clone of a Yamaha (as the Cagiva certainly had been) and neither was it a Honda copy, as the Paton was unjustly tagged – when in fact it was Honda that had copied Paton! The Elf V4 represented 500cc Grand Prix racing the European way, breaking new ground with technical innovation that worked – albeit by no means as radical as the series of hub-centre, Honda-powered Elf racers of the previous decade.

For a start, the Elf 500’s Swiss-made singlecrankshaft crankcase reed-valve V4 engine was extremely light and compact. It scaled a whole 7kg lighter than a Yamaha YZR500 engine at 37kg (Max Biaggi’s World champion RSV250 Aprilia V-twin motor weighed 30kg!) and it was 130mm narrower than an NSR500 Honda and 100mm lower top to bottom than the Yamaha. Unlike any other four-cylinder two-stroke 500 yet made, the Elf’s crankcases were split vertically rather than horizontally like all other 500GP motors of the day. Swissauto CTO Urs Wenger stated this was partly to improve crankcase stiffness, but mainly to enhance access to the engine – for example the crankshaft could be changed in just one hour. This was a key factor in determining the 108° include ed cylinder angle, which also allowed space for f four large reed blocks and a row of powerjet-equipped Dell’orto flatslide e carbs that Swissauto cleverly combin ned into a single bank – the team fitted 39mm ones on faster tracks s amd 36mm on slower ones, accord ding to Wenger. But while w everyone else called the Elf/swiss sauto engine a V4, Wenger insisted on o labelling it a ‘deformed boxer’, bec cause the two pairs of cylinders on each side of the motor fired together, opposed at 180 0° in terms of firing angle to their counterpar rts, just like the cylinders of a BMW flat t win. This resulted in the engine’s extrem mely distinctive gruff exhaust note from what t was effectively a pair of V-twins mounte ed side by side on a common crankcase and a firing 180° apart. However, Swis ssauto later introduced a Big Bang g version of the engine, with the firing fi order closed right up with the intention of improving rideability. “We’ve already got more power from the Big Bang motor on the dyno, but we’re not really sure yet why!” admitted Wenger to me when I rode the bike in 1996. “We started out at with 90° firing angle, but if the riders say it makes a big difference, we’ll try a 60° format. But if not, we’ll leave it at 90°.” Because of the extra vibration from the Big Bang version, Swissauto first needed to redesign the crankcases to incorporate a balance shaft in the 180° version of the engine, before messing about with the firing angle. This experimental motor was in the Elf 500 when I rode it, as raced by a solitary Chris Walker at Brno after team-mate Borja crashed there in qualifying, ruling himself out of the race with a hand injury. Fitting the balance shaft added 1.9kg in total to the weight of the engine – an acceptable penalty for reducing rider fatigue, as well as the risk of component breakage, said Wenger. Unlike the Japanese V4 500GP engines, the Elf/swissauto motor used a single

crankcase volume for each pair of opposed cylinders, resulting in a total of just six flywheels and four main bearings for the single crankshaft, whereas the V4 Honda NSR500’S single crank had five main bearings with four crankcase volumes and, of course, the Yamaha and Suzuki 500s had twin crankshafts, so a total of eight main bearings in all. On the Swiss motor, this feature not only helped reduce weight, bulk and friction, but was also a crucial factor in the engine’s impressive power output – over 190bhp at the clutch at 12,500rpm, according to Urs Wenger, compared to 185bhp from the Sidecar version in customer form. Speaking in 1997 Wenger said: “We have much higher pre-compression than any other engine with our crankcase design. But as well as good maximum power, this engine also has a lot of torque. We have over 200bhp at the clutch on the dyno, but the power characteristics aren’t satisfactory, so we must do more work on the electronics and cylinders before we run it in the bike. But the engine is still quite new, so we have lots of development still to come!” After debuting the bike in 1995 with peaky HH cylinders from their Sidecar motor,

complet te with light-switch power delivery and no powervalve p – that must have made life exciting g for Swiss test rider Adrian Bosshard – Swiss sauto had been working on developing their ow wn cylinders to be made in-house like all the rest of the engine, which did indeed arrive for the 1997 season. Before that, for 1996 the Elf 500 motor featured five transfer/ two exhaust e port Bartol cylinders, which the Aust trian rider/engineer who later built the KTM M 125/250 two-stroke GP contenders had prev viously developed for use on Yamahas. “Our Swissauto cylinders give more power and d incorporate an absolutely original flaptyp pe powervalve system, as different from the e others as our crankcase design is,” said Wenger W at Brno in 1996. “But reliability is a pr roblem at the moment, so we won’t race with th hem until next season.” The Bartol cylinders employed a c conventional powervalve, controlled by the usual electric motor via sensors monitoring throttle position and rpm. These were linked to a programmable Swissauto digital ignition, which was powered by a total-loss solid-state battery running without a generator, but boosted by four magnetic triggers inserted into one of the crankshaft flywheels, and a crankcase pick-up. Wenger revealed that for each gear ratio there was a different ignition curve, a different powervalve curve and a different powerjet curve, resulting in more than 1000 separate items of data the team had to programme at each different circuit to optimise performance. “Track time – that’s the biggest problem we have at the moment,” he said at Brno. “Each track we come to, we have no data, because it’s our first time there with a new bike, and we must start from scratch programming the different electronic systems, quite apart from the usual stuff like chassis set-up and jetting. Each race, usually only in the pre-race warm-up the bike begins to work well for the first time, and sometimes not even then. The only exception was Paul Ricard, where we did some testing over the winter. There, the fact that Borja was up to fifth place before he crashed shows how crucial this set-up time is. So, 1996 has been a learning year for us in making an investment I’m certain will pay off next season,” Wenger said. Any modern Motogp team would sympathise with this problem!

The Swissauto had a dual radiator cooling system with an external waterpump driven by a toothed belt directly off the right end of the crank, unlike its rival two-stroke Japanese race engines, while the clutch sat outside the crankcase on the other side of the motor and could be detached from its driveshaft via a cleverly-designed circlip system, thus allowing the team to change the entire clutch in just 30sec if it showed signs of slipping! Clutch removal allowed access to the extractable six-speed cassette gearbox, for which there was a choice of 36 different ratios in total, all of which Swissauto also manufactured themselves. Really, apart from the pistons from Japan, the Austrian cylinders used at the time of my test and the Dell’orto carbs, the entire Elf 500 engine was made on a mountain somewhere in Switzerland by some very clever people working with a superbly equipped machine shop housing state-of-the-art equipment. Swissauto was indeed a class act, and the only surprise is that they ended up being acquired by a company 6000 miles/10,000km away on the other side of the Atlantic, rather than one much closer at hand in Europe.