For Throwback Thursday this week, Alan Cathcart takes us on a ride on the amazing Swissauto ELF 500 GP racer, 25-years down the track...Test: Alan Cathcart Photography: Chris de Beer

This month Alan continues on his journey of riding the most legendary two-stroke GP 500s of the past. This time it is the utra trick, 190hp, 129kg Swissauto ELF 500 that was piloted by Adrian Bosshard, Chris Walker and Juan Borja, as well as Aussie Marty Craggill at the AGP…

The Swissauto ELF 500 wasn't the vicious accident-waiting-to-happen Alan been led to expect... Thankfully!

The Swissauto ELF 500 wasn’t the vicious accident-waiting-to-happen Alan been led to expect… Thankfully!

My chance to ride the Swissauto-engined ELF 500 25 years ago came the day after the 1996 Czech GP at Brno, halfway through its 1996 debut season. Having passengered World Sidecar champion Alain Michel on his Krauser-engined 500cc outfit (you will be able to read all about that next month – Ed) I knew this had heaps of power but a light-switch supply of it – on or off.


Check out the history of the Swissauto ELF 500 ROC here


Since paddock cynics had already dismissed the ELF 500 motor as just another modified Sidecar engine complete with razor-edge power delivery, I can’t deny I wasn’t looking forward a whole lot to the experience. Trepidation was the order of the day, not helped by Chris Walker telling me that it was about as different a ride as it could possibly be from the Ducati V-twin he’d ridden earlier that year in the British Superbike series!



The same cynics would have said that Borja’s enforced absence on race day at Brno with a hand injury incurred in qualifying for the race, proved how hard the ELF was to ride with the massive power from its sidecar-spec engine – over 190 bhp at that stage, at 12,500 rpm. But quite apart from the fact that ‘Baptiste’ stepped off the bike after losing the front-end on one of the more demanding handling tracks in the GP calendar, rather than highsiding when the power came in abruptly at the rear.


“When I came to ride the ELF there the day after the race, I discovered for myself it was definitely not as advertised.”


All Swissauto’s hard work in smoothing out the power delivery of its V4 engine for solo use was paying off. It wasn’t exactly a pussycat – no bike that powerful which carried full-time telemetry just to beat the 130kg class weight limit could be – but it certainly wasn’t the vicious accident-waiting-to-happen I’d been led to expect. In terms of transition into the strong powerband, the ELF was a lot more progressive than the last 500 four I’d ridden with an engine derived from a Sidecar application, the Fior 500 back in 1988. Funny – that was French, too.

"The progressive transition into the strong powerband from low down, reflecting all the hard development Urs Wenger and his team had wrought on taming the engine that year"...

“The progressive transition into the strong powerband from low down, reflecting all the hard development Urs Wenger and his team had wrought on taming the engine that year”…

Whereas persuading the Fior’s back wheel to hook up out of a turn when I rode it at Nogaro was a two-wheeled form of Russian roulette, the ELF was much more rideable thanks to its electronically-aided refinement. You just had to be sure you were ready for the strong rush of horsepower that was unleashed when you twisted your wrist hard with the tacho needle reading anywhere over ten grand.


Cassons Bell MX9
 

It was the sheer fact of having that much power available that made the bike a little daunting to ride – OK, a lot! – not the way it was delivered. The similarly single-crank NSR500 Honda was just as hard to master, and while I hadn’t by then ridden the RGV500 Suzuki for a couple of years, judging by the last time I’d done so that may have been harder still.

READ OUR OTHER 500cc TESTS IN THE RACER SECTION OF THE MENU



In fact, the ELF reminded me more of a works YZR500 Yamaha. It didn’t rev as high as the Suzuki, but it had really massive torque and a surprisingly powerful midrange, with a relatively progressive transition into the strong power band from low down, reflecting all the hard development Urs Wenger and his team had wrought on taming the engine that year. Moreover, on-track race comparisons with Borja aboard had shown the ELF to be actually faster on top speed than the factory Yamahas, and was on terms with the best Hondas. Some going for a new bike.


Check out the Chevallier RS500, Kocinski Cagiva 500, Roberts Senior YZR500 or Roberts Junior RGV500 tests by clicking on them…


The ELF began to make good power from just over 8,000rpm, but it wasn’t till the exhaust valve was fully open at just under 10,000 revs that it came on really strong, so in terms of selecting ratios for the cassette-type gearbox it was pretty peaky, with just under 3,000 revs of strong power. OK, very Sidecar-style – but it was the way Swissauto’s electronics had rationalised the actual delivery of all that horsepower which made it pretty rideable.


McLeods Shoei NXR
 

Jetted slightly rich for a journalist to ride, the delivery flattened out around the 12,500rpm power peak, but while there was normally some overrev available, apparently it wasn’t advisable to use too much of this – especially on the overrun – because the crankshaft didn’t like it, and this point was still work in progress on the engine when I rode it.



While it was true that the innovative engine design’s vertical crankcase split meant the crank could be changed in only one hour, the fact that it had fewer main bearings than anything else on the GP grid meant crank life was only 1,000km, and sometimes not even that. It was common practice for the ELF team to change cranks after each day of qualifying, and in fact the one on the test bike went soon after my final session on it – fortunately with someone else aboard when it locked up! This was the achilles heel of the bike at that stage of development, not the way the power was delivered.

"It wasn't till the exhaust valve was fully open at just under 10,000 revs that it came on really strong, so in terms of selecting ratios for the cassette-type gearbox it was pretty peaky, with just under 3,000 revs of strong power".

“It wasn’t till the exhaust valve was fully open at just under 10,000 revs that it came on really strong, so in terms of selecting ratios for the cassette-type gearbox it was pretty peaky, with just under 3,000 revs of strong power”.

Despite the reduced size of its compact engine, the ELF’s dedicated ROC chassis (quite different from the same firm’s contemporary YZR500 Yamaha frame) offered a pretty spacious riding position reminiscent of the NSR500 Honda – Chris Walker said his Ducati 955 Superbike was much more cramped! – with relatively low footrests that made it pretty comfortable for a taller rider: The result was that you felt part of the ELF rather than perched on top of it, and could move around on it really easily.


“You felt part of the ELF rather than perched on top of it, and could move around on it really easily”…


Sliding your body weight forward to stop it pulling a wheelie under hard acceleration out of a medium speed turn, tucking down under the screen for straight line speed, popping back on the seat at full arms stretch under hard braking to keep the back wheel somewhere near the ground and minimise weight transfer – all that was really easy on the ELF.



When I saw the Japanese carbon brakes fitted to the bike instead of the British or Italian black stoppers ROC’s Serge Rosset might have chosen for the ELF Eurobike, I’ll admit I was surprised. But that was until I rode it and found out why. By some way these were the best carbon brakes I’d yet sampled in well over a decade of using them since they debuted on the ELFe in 1981.



Their massive stopping power delivered the improbably short braking distances I’d come to expect from carbon discs, yet they had the sensitivity and feel of metal ones that let you to scrub off some speed if you went too deep into a turn, just by fingering the lever lightly rather than having to squeeze hard. Best of both worlds – but don’t think about the cost!

"The ELF stayed well balanced and could be laid into the bend almost as easily as the relatively diminutive V-twin Aprilia RSV400, even hard on the brakes".

“The ELF stayed well balanced and could be laid into the bend almost as easily as the relatively diminutive V-twin Aprilia RSV400, even hard on the brakes”.

The single-crank layout of the ELF’s V4 Swissauto engine had led me to expect the same sort of problems Honda experienced in getting the NSR500 to handle as well as it eventually did by then, especially with all that power on tap. But a combination of ROC’s chassis expertise, the Öhlins suspension and the small dimensions, reduced inertia and light weight of the Swissauto engine, all combined to overcome that.

In fact, the ELF’s strongest point was turn-in to a bend, where especially if you used the back brake first to load up the rear suspension and minimise weight transfer when you squeezed hard on the carbon brakes, the ELF stayed well balanced and could be laid into the bend almost as easily as the relatively diminutive V-twin Aprilia RSV400, even hard on the brakes.



It also changed direction really well in a chicane, especially if you hit the back brake again hard just as you were about to flick from one side to another in the middle, to stand the bike up. It was really well balanced, responsive without being nervous, and pulling the ELF upright sooner on the exit of a turn allowed you to safely get hard on the gas earlier, so you could use the fat part of the tyre to put all that power to the ground.

When after a dozen laps or so at Brno the 17-inch rear tyre (ELF had stopped using the 16.5 inch rear Michelin for the time being) starting to wear, so you could feel it start to ‘walk’ under hard acceleration exiting a turn like the uphill off-camber chicane before the finish line, it was really important to pull the bike upright before getting hard on the gas. Straighten up and fly right!

The ELF 500 changed direction through the chicane with speed and easy, but some front-end push was evident with Alan on the bike. We aren't saying that had anything to do with those big English breakfasts...

The ELF 500 changed direction through the chicane with speed and easy, but some front-end push was evident with Alan on the bike. We aren’t saying that had anything to do with those big English breakfasts…

Combined with the meaty midrange torque from the engine, all this put Borja’s Donington exploit into perspective. To get such a good result on a twisty track without any real straight could only happen with a bike that stopped and handled well, and had a controllable power delivery. I did notice that pulling the ELF upright on the back brake exiting a turn, meant it held a line much better on the gas, allowing me to accelerate harder, sooner.


Cassons Bell MX9
 

That was not only for the obvious reason, that I risked a highside through asking too much of the rear tyre’s edge grip in transmitting all that power, but also because if you gassed it hard on the angle, then it pushed the front-end and understeered towards the outside of the track. At first I thought this was because of my extra body weight compared to Chris, so after my first session I got the team to stiffen up the rear shock, to stop it compressing so much under acceleration.



Next time out, the ELF handled much better, but still pushed the front a little. The problem was there to be dialled out, perhaps by raising the rear ride height or playing around with the steering geometry, but Chris Walker admitted that at that stage of his career he was still pretty lost when it came to chassis setup. For someone who’d had his first-ever road race just a little over two years earlier, and had tied with Jean-Michel Bayle for the world record shortest time in going from Motocross/Enduro to a works 500GP ride on tarmac, this was understandable….

The ELF was losing five meters off the turns to the Japanese 500s in 1996. It would take until 1999 for this issue to be ironed out...

The ELF was losing five meters off the turns to the Japanese 500s in 1996. It would take until 1999 for this issue to be ironed out… To take advantage of the engine earlier, the bike had to be ridden in the mid range.

But what the ELF did seem to lack at that stage was the explosive acceleration I’d come to expect from a 500 V4 – especially a factory bike. Trap times had shown that top speed wasn’t a problem, even compared to the factory Japanese bikes, but the vivid zap out of slow to medium speed turns at Brno that I’d expected from a bike with this much power, was absent. Sure, the ELF 500 drove out of a turn OK – but it wasn’t till you were halfway down one of the Brno straights that you really got a sense of other-worldly speed that was ever-present when you rode an NSR500 Honda.



I might have thought it was just because the jetting was bit rich, except that watching Chris Walker in the race the day before locked in battle with the best of the privateers and the slow-starting Norick Abe’s works Yamaha, it was obvious this was a basic handicap – the ELF lost five metres or more on its rivals exiting a turn, before it began catching up halfway down the following straight. Four years of patient development by Swissauto were to eradicate this problem by 1999!

The bike Alan rode was carrying a balance shaft for the first time, in preparation for moving to a Big Bang engine.

The bike Alan rode was carrying a balance shaft for the first time, in preparation for moving to a Big Bang engine.

The temptation back then was to try to get around this acceleration hangup by riding the ELF like a 250, using a gear lower and buzzing the engine, but doing that resulted in problems with rear grip in those pre-traction control days, and popping the front wheel in the air, which may have looked spectacular, but also lost time. The ELF repaid being revved lower, so you could take full advantage of its excellent midrange torque. This problem was nothing to do with the basic nature of the ELF’s power delivery, for the fact that it only occurred under acceleration out of slower turns in the bottom three gears, rather than at the same rpm in faster ones using a higher gear, meant it was most likely airflow related, so perhaps the team needed to do more work on the airbox and carburation to resolve it.


“The temptation back then was to try to get around this acceleration hangup by riding the ELF like a 250, using a gear lower and buzzing the engine, but doing that resulted in problems with rear grip in those pre-traction control days”…


Personally, I reckoned those big 39mm carbs were to blame. The ELF 500 was basically over-carburetted in the same way as its Cagiva counterpart of the era certainly was, presumably in order to achieve those big horsepower numbers at peak revs. It’s no coincidence that the NSR500 Honda only used 36mm carbs, and I’m sure the ELF could have had better drive out of turns with smaller carbs fitted. I wonder if Borja had the smaller carbs installed that Urs Wenger admitted to me that Swissauto had experimented with fitted for Donington, when he beat all those Hondas?

The ELF used an ROC frame which was not the same as the ROC Yamaha YZR500 frame, rather a dedicated and co-developed unit.

The ELF used an ROC frame which was not the same as the ROC Yamaha YZR500 frame, rather a dedicated and co-developed unit. The single crank V4 did not suffer the same handling issues as the early Honda single crank 500.

The bike I was riding was the same one Chris Walker had ridden to 20th place in the Czech GP the day before, after scoring his first World Championship point for the team the previous weekend in the Austrian GP at the Salzburgring. Its engine was carrying a balance shaft for the first time as a preliminary step towards the Big Bang motor that Swissauto had under development. There still some vibration through the footrests, though Chris said it was much smoother than before.

The engine was anyway mounted in Silentbloc rubber bushes which ROC had made to contain the vibration, although the rear pair out of the six mounting points could apparently also be rigid to give a ‘semi-floating’ engine position, which ROC boss Serge Rosset claimed worked better at reducing vibes. The new version of the motor I was sampling had different crankcases, so ROC had had to modify the chassis to install the smoother engine. Worth doing. I didn’t really care for the gearbox’s shift action, though – it had a heavy, mechanical-feel to it and lacked the precision I expected.


“The 500 Cagiva’s gearshift felt similarly harsh each time I rode it, but at least by then it had a speed-shifter fitted to help counter this”…


The bottom line after riding the ELF 500 towards the end of its first season of competition, though, was that it was a project with a genuine potential future which was already repaying the hard work put into it. Thanks to the support of the French oil company, the valuable Euro-dimension had been restored to 500GP grids, bringing a technical breath of fresh air with it. This wasn’t an exercise in alternative technology for the sake of being different, but a genuine contender for GP racing’s top honours that was in the process of growing up so it could go play with the older kids.


Harley
 

To have achieved so much already in the bike’s development season must have been very rewarding for the ELF team. My Brno ride on their new 500 four showed they had a genuine contender on the grid – and subsequent events proved that to be the case, albeit with another name on the tank!

1996 SWISSAUTO ELF 500 ROC GP RACER SPECIFICATIONS

ENGINE: Watercooled 180 degree V4 single-crankshaft crankcase reed-valve two-stroke with contrarotating balance shaft and each pair of cylinders firing together at 180 degree intervals, 54 x 54.5mm bore x stroke, 499cc, 4 x 39mm Dell’Orto flatslide carburettors with electronic powerjet, Swissauto CDI, six-speed cassette-type gearbox, multiplate dry clutch


CHASSIS: ROC aluminium twin-spar frame, 46mm Öhlins inverted telescopic forks, aluminium swingarm with Öhlins monoshock and rising rate link, 23 degrees rake, 1410mm wheelbase, 2 x 320mm Mitsubishi carbon composite discs with four-piston Nissin calipers, 1 x 220mm Nissin steel disc with two-piston Nissin caliper, 12/60-17 Michelin radial on 3.50 in. PVM cast aluminium wheel, 18/67-17 Michelin radial on 6.00 in. PVM cast aluminium wheel


PERFORMANCE: Over 310 km/h, 192 bhp at 12,500 rpm (at clutch), 129kg with oil/water and telemetry, without 35-litre fuel tank


OWNER: ELF Huiles Minerales SA, Etagnières, Switzerland


Harley

THE SWISSAUTO ELF 500 ENGINE

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 was), and neither was it a Honda copy as the Paton was unjustly tagged as – when in fact it was Honda which had admitted to copying Paton!


“The ELF V4 represented 500cc Grand Prix racing The European Way, breaking new ground with technical innovation that worked”…


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.

The amazing V4 two stroke engine was like nothing people had seen before, amazing amounts of engineering knowledge went into creating it.

For a start, the ELF 500’s Swiss-made single-crankshaft crankcase reed-valve V4 engine was extremely light and compact. It scaled a whole seven kilos 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 – the crankshaft could be changed in just one hour, for example. This was a key factor in determining the 108º included cylinder angle, which also allowed space for four large reed blocks and the row of powerjet-equipped Dell’Orto flatslide carbs which Swissauto cleverly combined into a single bank – the team fitted 39mm ones on faster tracks, 36mm on slower ones”.



But while everyone else called the ELF/Swissauto engine a V4, Wenger insisted on labelling it a ‘deformed boxer’, because the two pairs of cylinders on each side of the motor fired together, opposed at 180 degrees in terms of firing angle to their counterparts just like the cylinders of a BMW flat twin. This resulted in the engine’s extremely distinctive, gruff exhaust note from what was effectively a pair of V-twins mounted side by side on a common crankcase, and firing 180 degrees apart.


Kawasaki
 

However, Swissauto later introduced a Big Bang version of the engine, with the firing 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 a 90-degree firing angle, but if the riders say it makes a big difference, we’ll try a 60-degree format. But if not, we’ll just leave it at 90.”

“Because of the extra vibration from the Big Bang version, Swissauto first however needed to redesign the crankcases to incorporate a balance shaft in the 180-degree version of the engine.”

Because of the extra vibration from the Big Bang version, Swissauto first however needed to redesign the crankcases to incorporate a balance shaft in the 180-degree 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 teammate 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 only 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.”


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 190 bhp at the clutch at 12,500 pm, according to Urs Wenger, compared to 185 bhp from the Sidecar version in customer form. “We have much higher pre-compression than any other engine with our crankcase design,” he said, “but as well as good maximum power, this engine also has a lot of torque. For sure our cylinders and exhausts aren’t yet as good as on the Japanese engines, but we’re competitive with them because of the correct fundamental layout. Once we get the rest right, we’ll be better overall – already we have over 200 bhp 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!”

Seven times World Sidecar Champion Rolf Biland with the LCR Swissauto outfit. Rolf was instrumental in the development of the Swissauto V4 engine.

After debuting the bike in ’95 with peaky HH cylinders from their Sidecar motor, complete with light-switch power delivery and no powervalve – that must have made life exciting for Swiss test rider Adrian Bosshard! – Swissauto had been working on developing their own 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 port Bartol cylinders which the Austrian rider/engineer who later built the KTM 125/250 two-stroke GP contenders had previously developed for use on Yamahas.

Early development stages of the ELF 500GP racer included getting the maximum out of the two-stroke engine.

“Our Swissauto cylinders give more power, and incorporate an absolutely original flap-type powervalve system, as different from the others as our crankcase design is,” said Wenger at Brno. “But reliability is a problem at the moment, so we won’t race with them till next season.” The Bartol cylinders employed a 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 pickup.



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 setup and jetting.


UMI Meteor 350
 

Each race, usually only in the pre-race warmup 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 setup time is. So 1996 has been a learning year for us in making an investment I’m certain will pay off.”

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 and could be detached from its driveshaft, allowing for a 30 second clutch change.

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 which came 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 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 6,000 miles/10,000km away on the other side of the Atlantic, rather than one much closer at hand in Europe.


Cassons Bell MX9
 

1996 ELF Swissauto 500GP Gallery


Triumph PSI temporary Q3
 


RatedR Parts
 


RatedR Parts
 

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