MCViewPoint

Opinion from a Libertarian ViewPoint

Luigi Taveri and Honda’s incredible five-cylinder 125cc Grand Prix racer: a tribute

Posted by M. C. on November 30, 2019

A trip down memory lane and old Hondas.

Two of the Honda pistons would fit on a credit card and with room to spare. Each of the four valves which fed the cylinders weighed less than 10 grammes – or the same as a couple of grapes.

A normal rev limit of 21,500rpm – and another 500rpm still left for the last-lap dash to the line

https://www.telegraph.co.uk/cars/features/luigi-taveri-hondas-incredible-five-cylinder-125cc-grand-prix/

No one with a love of motorcycle racing can be in the presence of Honda’s tiny RC148 and not be awed. Compared with the electronic sophistication, and immaculate finish, of a modern Grand Prix bike the Honda looks almost like an extremely well-made, home-built special – until the statistics are reeled off.

A normal rev limit of 21,500rpm – and another 500rpm still left for the last-lap dash to the line – an eight-speed gearbox and a race weight of 85kg (187lb) mean that the Honda “five” was the absolute limit of motorcycle engineering in 1965.

In every race, the Honda sounded as if it was operating on the last one per cent of what a motorcycle could achieve before it self-destructed – although in fact it was utterly reliable.

By contrast, the iconic, 250cc and 350c Honda six-cylinder engines always produced calmer, more controlled mechanical music – like a tenor singing soprano – while the “5” was a wailing, frenetic, Punk Rock lead singer.

What is all the more remarkable is that the RC148 was designed, manufactured and built largely without the aid of computers. Go to a GP today and the IT gurus are more important than the mechanics, but in 1964, Honda’s race staff were able to do remarkable feats of engineering with nothing more than a mechanical slide rule, log tables, drawing pen and notepad.

They also had an enormous advantage over modern designers: they sensed the engineering in the same way that a top chef feels exactly the amount of seasoning required to make a culinary masterpiece.

The RC148 came at a time when spring-makers could judge the precise temperature of a piece of red hot metal by spitting on it and watching how their saliva reacted. The RC148 did not simply appear on a sheet of paper in Honda’s drawing office: the Tokyo factory had a lot of experience of very high revving, multi-cylinder engines stretching all the way back to 1959 and the RC142 twin which revved to an astonishing, for the day, 14,000rpm.

However, by 1965 Honda was facing huge challenges from the two-strokes of both Suzuki and Yamaha. The battle raged across all the small classes – 50cc, 125cc and 250cc – and Honda was determined to defend the four-stroke cause.

Luigi Taveri - 125cc five-cylinder Honda Grand Prix bike
The RC148 gifted to Taveri by Soichiro Honda Credit: Carol Melling

The key to the “5” was Honda’s highly developed 50cc twin, which had a bore and stroke of 34mm x 27.4mm. Two of the Honda pistons would fit on a credit card and with room to spare. Each of the four valves which fed the cylinders weighed less than 10 grammes – or the same as a couple of grapes.

With a bore of 34mm, Honda hit on the idea that five 25cc cylinders would become a world-beating 124cc engine – in effect, two and a half 50cc twins.

Honda knew a lot about getting miniscule cylinders to fill effectively and very high-revving engines to stay in one piece and so it was comfortable with an engine spinning routinely to more than 22,000rpm. It was also very familiar with the eight-speed gearbox needed by the 125cc to keep it within the 5,000rpm power band.

Luigi Taveri - 125cc five-cylinder Honda Grand Prix bike
Taveri practises push-starting the RC148: “The “5” was incredibly difficult to start. The moment it fired you had to catch the engine with the throttle and then just feather the clutch until the motor would run cleanly – maybe 18,000rpm” Credit: Frank Melling Archive

The chassis followed standard Honda practice by using the engine as a stressed member in a duplex spine formed from steel tubing. Brakes were twin leading shoe drums – but aided by the excellent engine braking which the “5” provided the moment it was shut off.

Rhodesian Nobby Clark (sadly, also no longer with us) was the only non-Japanese mechanic to work on the “5” and remembered it with fondness. “I liked the “5” a lot – except for me having hands which were too big!” he said.

“Everything was so tiny that parts disappeared in my fingers, they were so small. The valves looked more like carpenters’ nails than poppet valves from a motorcycle engine.

“The “5” was a really nice bike and very reliable. We refreshed the motor every 800km (500 miles) with a new crank, pistons, valves and so on but the eight-speed gearbox was left alone.

honda RC148 125cc five-cylinder Grand Prix bike
The red line is set at 21,500rpm – although it would safely rev higher. The 124cc, five-cylinder was also a reliable engine Credit: Carol Melling

“People used to ask me for a piston for a souvenir but we always destroyed the crown because the design was top secret. The pistons arrived from Japan part-finished and we filed them by hand, and then satin-finished them with emery paper, to match the squish band in each individual cylinder head.

“This was an enjoyable job because part of my annual trade test for Rhodesian Railways was to file a 1-inch square section of mild steel round and within a tolerance of 5 thou [0.005 of an inch], so working on the pistons was not a problem.

“More out of caution than need, we would change the clutch about half way through a season but it never really needed it.

“The cycle parts were totally reliable. There was no real suspension adjustment available and the main work was cleaning the brakes regularly and we would change the steering head bearings after a wet race because they tended to get water in them.

Luigi Taveri - 125cc five-cylinder Honda Grand Prix bike
The diminutive Taveri demonstrates the streamlined tuck essential to success in the smaller capacity classes Credit: Frank Melling Archive

“The only real problem with the bike was that it was really sensitive in terms of carburation. This is why Luigi never went well on the “5” in the Isle of Man. The difference in altitude between the lower sections of the course and the Mountain was enough to prevent us getting the carburation exactly right and so the “5” always ran rich.

“The Japanese had mixed feelings about the “5”. They liked the bike but they looked at [the success of] Bill Ivy and the four-cylinder Yamaha two-stroke and thought that the writing was on the wall for four-stroke GP bikes – at least in the smaller classes.”

So much for the magic ingredients, but what was it like to ride the “5”? The answers came directly from Honda’s most successful racer in the lightweight classes, three times World Champion Luigi Taveri.

Five decades after he last raced the RC148, the eyes of the elegant Swiss gentleman racer lit up at the mere mention of the “5”.

Luigi Taveri - 125cc five-cylinder Honda Grand Prix bike
Taveri on the grid at Assen Credit: Frank Melling Archive

“For me, the “5” was the best of all the Hondas I raced. It was the most difficult to ride but also the most satisfying. I beat the best riders on the best 125s in the world so I can only think good things about the “5”.

“It was also the most difficult bike to ride. Even starting it was very, very hard. In those days, we had push starts. I would pull the bike against compression in first gear and the moment the flag moved even a millimetre I would be off. But even surrounded with noise and tension you had to have a completely clear head because the “5” was incredibly difficult to start.

“The moment the bike fired you had to catch the engine with the throttle and then just feather the clutch until the motor would run cleanly – maybe 18,000rpm.

“After I retired, Barry Sheene tried a lap on my “5” and he couldn’t even start the bike, although he had raced Suzuki 125cc twins.

Luigi Taveri - 125cc five-cylinder Honda Grand Prix bike
Even 55 years later, it’s still hard to believe that there’s a five-cylinder engine under the RC148’s slim petrol tank Credit: Carol Melling

“The “5” was a beautiful bike to race. It handled very well and was extremely reliable but it had to be kept between 21,000rpm and 22,000rpm to be at its best.

“It would rev on safely beyond 22,000 but it went slower, while below 16,000rpm there was a good chance it would stop running all together.

“The noise was incredible. After a race, I couldn’t even hear Tilde [Luigi’s long-time wife and friend] speak to me. Even on the following morning, I couldn’t hear anything.

“The “5” gave me my happiest memories but I now have to wear two hearing aids!

“I enjoyed a very, very close and happy relationship with Honda and I am still in contact with my old GP mechanics even now.

Luigi Taveri 
Taveri displays a photo of himself and Soichiro Honda after securing another 125cc world championship title for the Japanese company Credit: Carol Melling

“When I decided to retire, Mr [Soichiro, company founder] Honda gave me a 250cc “4” and a “5” as retirement presents and I could not ask for more.”

Over the last 40 years, I have been very privileged to meet, and work with, some of the greatest motorcycles racers of the time but Luigi will always hold a special place in my mind and heart.

Even in old age, he remained what he was at his glorious peak – passionate, determined, smiling and enthusiastic, intensely courteous and modest but most of all a true gentleman.

The whole world, not just the motorcycling fraternity, is poorer without him.

Luigi Taveri passed away on March 1, 2018 at the age of 88. Taveri, who won three 125cc World Championships in 1962, 1964 and 1966, was the one of the greats in an era of superstar riders and the most exotic motorcycles ever built. Frank Melling was the last journalist to talk to Luigi about the incredible Honda “5”.

 

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