The Sheene Machines (Part 2/2)

Published: 22 August 2016

He liked his handlebars set wide and preferred aluminium crankcases, Heron Suzuki mechanic Martyn Ogborne reveals the secrets behind Barry’s winning bikes 

We all know the story of Barry Sheene’s 500cc Grand Prix world championship success in 1976 and 1977 – at least from the rider’s point of view. But the rider is only half the story. Sheene also needed the right bikes underneath him to make it happen and these are the two machines that took him to his two world titles. They’re currently in the UK on kind loan from the Sheene family residence in Australia and MCN was given exclusive access not only to the bikes but also to the man who made them work – Bazza’s legendary chief mechanic, Martyn Ogborne. We spent a morning poring over Sheene’s RG500s in minute detail with the one man who knows them inside out.  

TOP STORIES

MCN: How different was Sheene’s factory bike to the production racers his team-mates rode?

MO: On top speed, the production bike was almost the same but the works bikes could get in and out of corners quicker because of their weight advantage. Where the production racers had aluminium, we had magnesium and where they had steel, we had titanium. 

MCN: How did Suzuki find 5bhp more for the ’77 bike to take it from 114bhp to 119bhp?

MO: Transfer ports, doing work inside the carburettors – we took the carburettors off the XR23 and put them in the 1977 XR14 bike.

MCN: Can you tell us about the XR23 and XR22 bikes?

MO: Well, the only changes on the ’77 bike were re-shaped bodywork, the Kayaba shocks, and an altered swingarm that allowed the shocks to fit (because a V was cut into the arm to allow the shock to fit, a bracing arm was added underneath, which later became standard). Power was also up by 5bhp and the rev limit had dropped from 11,000rpm to 10,800rpm because of the different porting. What most people didn’t know was that Suzuki had a completely new bike waiting in the wings should it be needed in 1977. If the Yamahas started disappearing into the distance they would have brought it out but they didn’t so there was no need. It was dubbed the XR22 and was the sister bike to the XR23 - which was a 652cc bike built for the Anglo-American Match Races. Barry was furious that he couldn’t have it because he’d tested it before the season started. But Suzuki wouldn’t give it to him. In Japan, they only show what they need to show.

MCN: So was Barry disappointed when he first rode the ’77 bike because there were so few changes and he knew there was a better bike waiting in the wings?

MO: Yes, when he first rode the ’77 bike he was like, “F*** – is that it?” Because he’d already tested the XR22 he said he didn’t want the XR14. I could understand his anger because Suzuki had effectively gone, “Here’s what you could have, but here’s what you’re going to be riding.”

MCN: Can you tell us about the Kayaba ‘golden shocks’ which were one of the biggest changes on the ’77 bike?

MO: Barry didn’t like them. He never got on with them because they were just a different idea for him to understand. They were much lighter because there were no springs in them – it was just nitrogen gas and aluminium blocks and seals inside. They looked quite futuristic but were actually simple. Unless a Kayaba guy came with them, the Japanese Suzuki guys didn’t always know everything about the shocks and Barry didn’t like that. It gave him an extra level of work to do and in those days we’d only get four practice sessions before a Grand Prix.

Many of the circuits were road circuits like Spa or Assen and you can’t hire road circuits to test on. Barry already had to qualify, get the tyres worked out, get the transmission and jetting worked out – so he didn’t like throwing in a new component like the shocks. He’d be like, “Where’s the f****** Japanese test rider?” but the test riders weren’t at a level where they could race in Grands Prix so he had too much to do and he hated using anything that hadn’t been properly tested.

All our pre-season testing was done in Japan. We found a circuit called Tsukuba, which was absolutely brilliant and had every kind of corner and bump imaginable. The Japanese hated it because the bike would come back with all the lock-stops missing off the frame but it taught us loads.

MCN: Can you point out any aspects of either bike that were Sheene-specific?

MO: Well, there are the handlebars, which are like bloody aeroplane wings. We would always try and bring them in closer to the bike but Barry wanted them out. That was a horrible way of riding because it was so un-streamlined and it also meant the levers would bang into the bodywork at full lock, which the regulations did not allow. We cut away the bodywork, but they still made contact so we’d pull the bars in to get through scrutineering and then bring them back out for Barry afterwards. I later realised that all Barry’s strength was upper body strength because he couldn’t use his legs properly so the wider bars allowed for more leverage and he compensated by doing all the steering with his arms. The bar grips originally had little lips on the end but Barry didn’t like them so we took them off. There’s a catch-bottle for carburettor overflow down the bottom left side of the fairing because Barry had a big get-off in 1974 and broke his wrist, before we had catch-bottles. Because the bike runs side-mounted floats, they overflowed and caused him to crash so he insisted on a catch-bottle after that.

MCN: What was the RG500 like to ride?

MO: The power delivery was vicious. You’d hit about 9800rpm and it was just BANG! It was frighteningly quick. What’s funny was the way it pulled to 11,000rpm. You know the way a bike will snatch forward if you whack the throttle open in first gear? The RG500 did that in sixth as long as you were in the powerband! The brakes were nowhere near as good as today’s carbon brakes but the bike was so light (132kg) it didn’t matter.

MCN: Why are the bikes on treaded tyres?

MO: Because Michelin don’t make 18in slicks any more. The only way we could fit slicks would be to change to 17in wheels and that would be even less authentic.

MCN: Was there anything about the RG500 that Barry didn’t like?

MO: He believed that the good top speed of the production bike was due to them having aluminium crankcases while ours were magnesium – which were 6kg lighter than those of the production racer – so Barry demanded aluminium crankcases. We’d show him the bhp figures and he’d say, “I don’t care – I want to try them!” So Suzuki gave him a set of production crankcases to humour him. We tried them and, of course, the bike was no faster. But it was just something he’d got into his head and he wanted to be absolutely sure that no-one else had an advantage.

Tech Specs

1976 Suzuki RG500 XR14
Engine 464.69cc liquid-cooled square-four rotary-valve two-stroke
Bore x stroke 54mm x 54mm
Compression ratio 8:2 to 1
Lubrication Fuel pre-mix (20:1 ratio)
Carburettor 4 x Mikuni (magnesium)
Ignition System Nippon-Denso CDI Magneto, twin ignition coil
Max power 114bhp @ 11,200 rpm
Max speed 183mph
Clutch Dry multi-plate
Transmission 6-speed, constant mesh
Chassis Steel tube duplex cradle
Steering head angle 25:4 degrees
Brakes front 2 x 295mm floating steel disc
Brakes rear Ventilated 220mm cast iron disc
Tyre size front (inch) Variable using cast magnesium 2:50  x 18 rim
Tyre size rear  (inch) Variable using cast magnesium 3:50 x 18 rim
Suspension front Kayaba telescopic, air assisted, internal spring, damped, 35mm inner tube, 130mm stroke
Suspension rear Kayaba oil damped, external spring, 85mm stroke, aluminum box section swinging arm
Dry weight 132kg
Race wins 3 (France, Austria and Nations). The 1977 bike won the Venezuelan GP, West German GP, and French GP

You can see Sheene’s bikes up close at these these biking events:

  • British GP, Silverstone, September 1-4
  • Classic Suzuki Sunday at the Super Sausage cafe in Towcester, September 11
  • Classic Show, Stafford, October 15-16
  • Classic Bike Live, Peterborough, October 29-30
  • Motorcycle Live, Birmingham NEC, November 19-27

 

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