Fast Bikes notes & ideas



A new racing formula is one of the few occasions when we get to see something interesting and original, before everyone starts to play follow-the-leader. It’s also open season for journalistic bullshit, and I can’t resist adding my two penny worth (and on FB pay, that’s probably exactly what it will be).

At first glance, the four-stroke GP Yamaha looks like a stop-gap solution, requiring little thought and no new tooling, just a re-hash of WSB kit. Historically, this has been a very good way of approaching a new racing formula. While the others are busy trying to iron out all of the bugs from their fancy new tackle, the winner just plods along with his old, reliable, well-sorted stuff – even though it might be relatively overweight and underpowered. The best “hare and tortoise” example was when the Formula 1 car boys changed from a 1500cc to a 3000cc formula in the 1960s; the first championship was won by Jack Brabham using a crude V8 adapted from a production car. The fancy V12s, V16s, and even H-16s (one flat-8 mounted on top of another) were all either too unreliable or not ready in time. So, is the simple Yamaha a winner? Probably not; it’s difficult to imagine the mighty Honda Racing Corporation being “not ready”.

Honda are perhaps being not quite as radical as they would like you to think. At first glance, their V5 engine would appear to be quite a show-stopper, but “odd” vees are nothing new – Honda were running two-stroke V3s years ago for Freddie Spencer, Ron Haslam, and others. I’ve often thought that grim memories of trying to keep up with them are the main reason that Kenny Roberts Snr’s team runs a V3 now. The Hondas were, incidentally, not dissimilar to a DKW engine made in 1954, so there’s nothing new.

It’s not actually that difficult to adapt an RC45 engine to carry one more cylinder, and if the layout proves successful, the gimmick will have unbeatable marketing appeal. A V5 is a very cunning combination of looking new and radical whilst being based on proven technology. The RC45 was a brilliant bike, perhaps the ultimate 750 racer of all time – but it was unsuccessful because of being forced to race against 1000cc bikes in a world series with bent rules run by Italians for Italians. Honda never actually wanted to build a V2; they just worked out that there was no alternative to building a Japanese Ducati if they wanted to win anything in WSB. On the “nothing new” theme, I can’t resist mentioning that AJS made a water-cooled 500cc V4 in 1939, but it was effectively killed off because it was designed to run with a supercharger, which was banned in a crafty rule change designed to keep Nortons on top.

Still, if they say that two’s company and three’s a crowd, what on earth does five add up to?

I used to work with Peter Williams, the noted designer and rider of a series of radical works JPS Norton twins. One of Peter’s life-long beliefs is that two cylinders are plenty for any bike. I found that pretty bizarre around the time I first met him in the 1980s, given that things like FZ750s were then ruling the roost and Ducatis were only marginally more desirable than the Norton twin which had tried so hard to kill poor Peter in the big get-off that finished his riding career.

On the face of it, the Honda V5 is the perfect package for ultimate power. But are GP races going to be won by ultimate power? Probably not. If everyone has as much power as the tyres can handle, it’s the smallest and lightest package that’ll get to spray the champagne over the podium poonani.

If you want small and light, the V2 is the way to go. Or is it? Something which I hadn’t realized until I started designing the Lionheart is that having a narrow engine doesn’t do you any good once you get below a certain width, because the rider’s knees are going to be wider anyway. Even the lankiest rider, with his legs clamped tightly together, is going to measure more than 350mm across the knee area by the time you’ve allowed for a few layers of leather, some padding, and knee-sliders. So why make the engine any slimmer than that? Also, in the racing crouch position, the rider’s elbows will be in front of his knees, and you can’t get your elbows any closer together than your ribs. The width across the elbows will be pretty much the same as the shoulder width, which is quite large these days because of all the body-armour carried in that area.

So, though the Britten twin was commendably narrow, especially with its radiator under the seat, the head-on pictures of the bike printed in all of the bike comics missed the point, because with a rider on board the whole plot wasn’t any smaller (in frontal area terms) than an RC45.

Twins aren’t without their own packaging bothers, of course. Ducati have had a problem for years with the big gap in the middle of their 90 degree vee, and also with finding clearance to prevent the front wheel from clouting the front cylinder head. Doubtless the Aprilia engineers had a good look at it before they asked Rotax to come up with the 60 degree twin for the RSV – on paper, pretty much the ideal package, but Rotax cut things very fine and they have been paranoid ever since – the road version of the engine is massively detuned for reliability (oops – I don’t think I’m supposed to know that) and it needs a big (power-sapping) balance shaft to stop it rattling.

So how about a parallel twin like the JPS Norton, the NVT-Cosworth Challenge, and the 1948 AJS “Porcupine”? The only reason is history – I can’t think of any racing parallel twin that wasn’t an embarrassing flop.

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