Four-stroke GP retrospective

MotoGP is about to see another change with a move to a 1000cc engine limit, this change is seen with excitement. Here we look back at the trepidation of the four-stroke GP before the class changed in 2002

Back in 2002 MotoGP shifted away from the 500cc two-stroke that had been the mainstay of the class for many years. From their introduction the 990 four strokes put on an exciting show for the adoring audience, but following safety concerns the 990s were downgraded to 800s. What took precedent in the MotoGP class since the decrease is engine capacity and increase in rider aids has been a monotonous spectacle.

Unlike the excitement of the incoming move to 1000cc for 2012 the motorcycling world were uncertain of the original four-stroke change. This feature from 2001 sums up the intrigue, distaste and excitement before the MotoGP class was born.

Why? Well the GP people have been addicts to the smell of two-stroke pre-mix and the sheer purity of an engine type which gives a power stroke each cycle since the days of Barry Sheene. Almost exclusively four-stroke in the 1950s and '60s, 500GP racing soon came to love its voraciously thirsty but volumetrically efficient two stroke-engines, which were well suited to racing and expert DIY tuning. So, in a crank-shell, GP people grew to hate (I mean really hate) even the idea of four-strokes.

So when GP promoters Dorna announced that four-strokes were going to be brought back into the World Championship fold as of 2002, it did more than raise a few eyebrows.

But times and opinions can change very quickly and everyone, it seems, is gung-ho for it now. Even SBK stalwarts and GP outsiders, Kawasaki and Ducati, have joined the Motorcycle Sport Manufacturers' Association (MSMA), previously the Grand Prix Manufacturers' Association, simply because they can sniff a chance to pit their four-stroke race departments and established technology base against the Big Hitters in the GP world.

Some of the manufacturers have been very sharp out the blocks with their new four-stroke challengers - to the point whereby here we are in late 2001, with four full-on entrants from three existing bike factories and one from the fabled land of Formula 1 - plus Ducati, who have made public their full intent to build their own all-new twin. How could anyone not be bowled over with excitement with the whole idea?

Well despite any journalist's sense of natural scepticism, I have to confess a certain frisson of excitement at the prospect, tempered with a dread at what would become of the sport if it all fell flat. Although yours truly plies his trade of wordsmiffery mainly in the WSB paddock, I am as keen as anyone in the world to have a technologically interesting GP class once more.

I will, like most, be sad to see the eventual demise of the savagely-powerful 500 vee-four strokers that only a few men on this planet can rightfully be able to claim to have mastered, but you could argue that advancing technology, lead-free gas and a 15kg weight add-on had chased the most ferocious fires from the dragons' bellies long ago.

Why shouldn't we get excited about four strokes, anyway? Just imagine what GP racing could be like from now on. Modern-day Guzzi V8s, Honda V6s that handle, monocoque-framed, oval-pistoned 32-valve uber-racers, and F1 technology used for a more worthwhile purpose than sending the world's TV viewers to sleep of a Sunday afternoon.

We could be marvelling at the beryllium con-rods, one-off titanium everything, ceramic barrel-style throttles, fully interactive EFI systems, fly-by-wire throttles. Someone, somewhere, will no doubt find a use for stealth technology. But after all that, is it just a traipse back to the past?

Whoever first dreamt up the idea of reverting the GP Championship to the world of valves and camshafts is completely immaterial now. The idea has now become a fait, semi-accompli. At present Honda and Yamaha have bikes lapping the test tracks which look pretty much like the finished article. A bit of detailing here and development there and the first of the new four-stroke GP bikes will be growling away on the startline next year. But here's the big scoop. So far nothing has been that new or revolutionary. Not really.

Honda has reverted to its favoured format and made an interesting vee-four, the RC211, with another cylinder in there to exploit the quirky technical regs, which group bikes of odd cylinder numbers together, in a weight limit the same as a machine with one less (even numbers) of cylinders. Or in simpler terms, odd numbers of cylinders good, even numbers theoretically not so good. But that's about as odd as it has got so far.

Yamaha have made an all-new and smaller hybrid version of their proven GP/SBK machines, and called it the M1. It's a sort of a factory brewed R71 reader's special, like you can see riding up and down... well... the M1. Yamaha has used its full gamut of technical trickery, but, as far as we can tell, nothing that new or radical. It's a parallel-four with fuel injection and 20-valves. Suzuki declared their intention to join the party at the Catalunya GP, with a vee-four.

Sauber/Petronas, the first of the F1 boys to chuck their hats into the ring, have made a prototype in-line transverse three cylinder with little sign of anything more trick than a reversed head, with the EFI system sucking cold air from the front.

Frankly, nobody so far seems intent on re-inventing the wheel. Or the engine. And here's the reason. There seems little point, not unless you are determined - like Ducati is - to build something of less than three cylinders.

You simply don't need pneumatic valves, oval pistons or much in the way of mega-tech to make a contemporary four-stroke as powerful as you want. Or certainly as powerful as current tyre and chassis technology can handle. Yamaha and Suzuki haven't even deemed it necessary to go for the cute 'extra cylinder' trick to help them reach their target horsepower and stay within the rules.

With 990cc to play with, weight limits which are reasonably low compared to World Superbike's universal 162kg, and an eye on the future in terms of costs to potential customers for your race bike - and hopefully spin-off road bikes - the factory race shops may have to concentrate their efforts on reining themselves in.

In simple terms, there seems to be no problem getting almost any engine format allowed under the rules to punt out at least 200bhp, without trying really. 250bhp is a realistic output and a lot more would surely be possible right now if anyone did want to build a 990cc V6. Bear in mind that in some experimental F1 engines at the moment they're squeezing 750bhp out of 1.6 litre engines, and it puts what is actually possible into perspective.

However, the final nail in the power-at-all-costs coffin for the GP bikes is the fuel limit of 24 litres. No point making a V6 if it runs dry with one lap to go every race. So if you're looking for super-high tech you may just be peering in the shop window a bit early yet.

After all, even the ageing Kawasaki 750cc four-cylinder World Superbike, based on an obsolete carburetted roadster with roots in the early 'nineties, still spits out a rasping 175bhp at the tyre. And that's complete with an engine spec for the slower circuits which includes steel intake valves, right out of your local Kawasaki dealer's parts shelf. Give it another 240ccs, let them cut and shut the chassis and Kawasaki could go GP racing with an already proven bike (198mph top speed at Hockenheim in 1999, remember.) And they could do it like now, never mind next year. Only they can't. They aren't allowed.

As you almost certainly know, the new GP four stroke rules make it virtually impossible to use existing production parts. So far, anyway. What are allowed are prototypes, although as Yamaha have shown - with the public unveiling of their M1 at Catalunya - you can use as much conventional technology as you like.

Why have Yamaha done that anyway? Lots of reasons, among them, cost and speed of development - to get the things on the grid and then worry about the technological revolution at a later date. If at all. It also maintains their link to their roadbikes, which was part of the whole reason for going four-stroke in GPs in the first place.

But trickery simply isn't necessary to get the performance that conventional chassis and tyre technology can handle. And racing costs a lot of money, so why spend more than you need on the engines? Even if now you can use part of your R&D budget directly in racing and road bike spin-offs, instead of wasting it on two-strokes that you never even sold to the public.

Most of the manufacturers seem to have that sussed already and the results are initially disappointing for the ultra-tech heads, although enticing enough for the rest of the world. Maybe we will see a radical solution in someone's engine room, but it appears that it will be complication for complication's sake.

The area in which we may see the most feverish activity is in the easily-overlooked chassis department and, as any race technician will tell you, you include tyres in that equation.

Consider the position of chassis design now. We have top level GP and factory Superbike riders complaining of chatter from the front and a frequent inability of the tyres to last race distance in anything but the way they would like. "The tyres went off and I had to drop back" is such a common phrase in the paddock that most riders may as well stencil it on their leathers. Few riders in GPs complain about a lack of power, no matter how much they may ask for more all the time. They always talk about chatter, balance, set-up and tyres. Especially tyres.

One look at the Superbikes, which have got around 170bhp, shows the point, with this year entire race results having been decided on the type of tyres the front runners have.

In the Michelin-only 500 grids, (another thing set to change with Bridgestone and Dunlop coming back in) the story is the same, plus there is the even more extreme problem of finding a perfect chassis set-up.

Arguably, the limit on GP times and to a lesser extent Superbike times, has been the chassis and tyre progress, not anything to do with power outputs themselves. The trick is, obviously enough, to get and keep that power on the ground for longer, minimise the time spent braking and cornering and get the throttles opened earlier. That is how to go fast in a single lap - and every lap. The word all the riders use is balance.

A hell of a lot will depend on tyres and the ability of the manufacturers to produce durable, sticky rubber for all track conditions. Michelin have been rumoured to have tested a whopping seven-inch-and-more rear tyre rim, in an attempt to put more rubber on the road when leaned over. This would allow the rider to feed more of his newly-gained excess horsepower onto the road earlier, and, with more rubber on the road, let the tyre run cooler and thus last longer.

On current tyres? You can have - basically - grip for a few laps or no grip for 25. An appalling Hobson's choice, and yet another reason not to build-in too much horsepower to the engine. Honda have apparently had to think again with their four-stroke chassis, as they cannot get their RC211V to do more than a few laps without wrecking the tyre . Hence only an engine - and not complete bike - launched so far, despite having tested for months.

Possibly another reason why we may never see an obsession with outright power, and the never-ending F-1 style trickness which produces it, is the nature of modern circuits. There are now precious few opportunities for the current GP riders to use more power than their sub-200bhp already bikes have. We have reached the point whereby few tracks will give any of the future megabikes we are talking about the chance to fully stretch their 200bhp+ legs.

The fastest circuits on the GP calendar are Assen (a 110mph lap record average) and Phillip Island (107mph lap record). Even Suzuka and Mugello's 103mph averages are probably as much about high corner speed than outright engine power. So please deliver unto us a safe Spa, a safe Salzburgring, a return to Monza, an unmolested Assen and Hockenheim so we can see what the new bikes can really do. Yeah, right. Dream on.

Fitted with glue tyres that last forever, the new generation of GP bikes could really do something about using their new potentially vast power outputs, but more acceleration in a conventional chassis generally means more wheelies, which means cutting back on the throttle so you don't flip it, or lose momentum, or adopting traction control - negating the need for all that power in the first place. Add in the fact that the more common, short, twisty tracks mean that you have to run lower overall gearing and the propensity to wheelie over the top with 200bhp gets even greater.

Lengthening the wheelbase would help, but then that would slow the steering; no good when 80 per cent of the track length consists of small radius corners and chicanes, where a flickable machine and corner speed is the optimum.

Traction control is a much-talked about addition to some bikes now and is expected on these bikes, with the increasing use of ever-impressively complicated EFI, to come into its own. Well, yes, by some. But not by the riders, who want to control wheelspin manually, for their own spectacular ends. How about it, Mr McCoy?

Braking advantages have already almost been taken care of now, with the limiting factor being the wheelbase of the bike again. You could easily spit the rider straight over the handlebars with the carbon brakes on GP bikes now. The reason they hop and skip on the way into the corners so much is little to do with the bumps they encounter, but because the brake rotors produce so much power the bike is on the point of stoppie all the time.

Assuming that even if you do have a higher speed on approach to the corner, thanks to your 250bhp, you will have to brake earlier, negating all of the good work done by the extra power down the rapidly-shortening main straights. Wonderful isn't it? Just when you think you've got it sussed, everything else conspires against you.

Which makes the science of making motorcycles go faster - in real racing conditions - not so much of a science at all. More an intuitive circus novelty, juggling and high-wire balancing all wrapped into one fragile endeavour. Not quite a black art, but not far off it. And that appears to have little to do with whether there is a two or a four-stroke engine producing the forward motive power.

But the question remains: will GP four-strokes actually work? More to the point, will they beat the two-stroke 500s, which will overnight be seen as cheap to run and still form the majority of the grid for the first couple of years at least? Will anyone be able to pay the increased costs of racing the four-strokes in the first place, especially if theirs gets beaten week in, week out? Bike racing is not F1, and cannot attract anything close to their sponsorship funds, despite the relatively affluent current GP paddock.

And then there is the real litmus test. Will four-strokes inspire the spectators and capture a larger public imagination? So far, yes, but we'll never know until it actually happens for real on the racetracks and the whole experiment could just as easily fail as succeed.

But let's look on the positive side. It could also be close, exciting, technically innovative, broaden the appeal of bike racing in general and best of all for existing fans, sound absolutely fan-bloody-tastic. The Honda, for example, makes an incredible noise, like a plasma chainsaw simply ripping the very molecules of the air apart as it banshees past. It actually sounds like two bikes, not one, and very loud bikes at that. The Yamaha sounds like a rule-breaking Superbike on full chat. The Suzuki will bring its own aural stimulation, with good old-fashioned V4 funk, the Sauber will sound like a Dornier bomber on final approach. And finally, the GP paddocks will reverberate to the spine-tingling thunder of Ducati's V-twin marvels.