Pitman’s XS11
Chain-drive rocket
The shaft drive XS11 Yamaha was never conceived as a race bike, but that didn’t stop it winning countless Production races from 1978 – at a time when the Unlimited Production class was the hottest and most ferociously-contested event on most programmes.
But the nascent
Superbike category was another thing altogether – the domain of home-brewed rockets like the Syndicate Kawasaki and the Hone Suzukis, particularly in the NGK-sponsored Victorian Superbike Championship which morphed into the national title in a few short years. In this class, the XS11 was simply off-spec – the shaft system too heavy and the machine itself ungainly. However over the summer of 1980/81, Yamaha Pitmans in Adelaide – a distributor with close ties to the factory in Japan – decided to rectify the situation. In Greg Pretty, their contracted rider, they had a man of outstanding ability and determination, who weighed just 53 kg, just what was needed to make the portly XS1100 competitive in Superbike trim. But there were other issues… To start at the beginning, Yamaha had retreated into its shell following consecutive disasters with the twin cylinder TX750 – the company’s first four stroke – and the TX500 – its first twin cam design, and had guardedly prepared to rectify the situation (and its badly tarnished image) with its first fourcylinder four stroke. This was the XS1100 (or XS 1.1 in USA) that broke cover in late 1977, designed first and foremost as a luxury tourer. That is, until Yamaha Pitmans got hold of it. Mal Pitman, the technical chief of the company’s racing efforts, explains the process that ultimately resulted in the XS1100 Superbike. “In December 1977 Yamaha brought a crew of a technician and three riders from Japan, and we tested the bikes in the eastern area of South Australia; we went up and down the border with Victoria, 650km rides each day. They wanted us to do over 180km/h all the time, so they could check the durability of the engine. This was the middle of summer, 40 degrees ambient with the road temperature up around 60. The rear tyres were lasting 650 km and they were shredded. We basically brought all the 17 inch tyres we could find in Adelaide. “We had a good rider in Greg Pretty – he was one of the guys that tested the suspension with us – but he wasn’t familiar with the XS1100 and had always ridden Kawasaki 900s. On the first day he went into a corner two fast, and not being familiar with the XS11, shut the throttle and down he went, decked the bike. When you close the throttle on a shaft drive in the middle of a corner, the bottom drops. When he crashed that bike, the Japanese really wanted to know if their rollover sensor, or tilt angle sensor, had worked, and had cut the engine. So tongue in cheek I told them that when I got to the bike, it was stopped. It was also in several pieces as well! So he learned how to ride the bike and when he went onto Production Racing, he won everything, but the Superbike was something he really wanted to ride because they had more horsepower and he was a horsepower nut.” Pretty and the XS1100 instantly became the major force in the 1978 Production Racing season, winning the prestigious Advertiser Three Hour in April, and two weeks later, the Perth Four Hour, this time paired with Mick Cole. In September, Pretty took out the Surfers Paradise Three Hour, the traditional curtain raiser to the ‘big one’ the Castrol Six Hour at Amaroo Park. Teamed with Jeff Miller, Pretty’s Pitman’s team looked a shoe-in for the Six Hour, and led the race until Miller crashed the bike and put it out. Although devastated, the Pitmans team shifted their attention to helping the Avon Tyres squad, which was also running and XS1100 for Jim Budd and Roger Heyes. Between them, they pulled off a master stroke by changing the rear wheel at half distance and won the race. The amazing Pretty commenced the 1979 season where he had left off in 1978, winning the Advertiser Three Hour again (and covering five more laps than the previous year, on the same bike), then snatched the Perth Four Hour, partnered this time by Jeff Parkin. Teamed with 1978 winner Jim Budd, pretty and the Pitmans XS1100 again went into the Castrol Six Hour as firm favourites, but lost out to the Suzuki GS1000 of Alan Hales/Neil Chivas, who went through the race on one set of Pirelli tyres, while the Pitmans Yamahas needed a rear wheel change and finished second, three laps in arrears. Pretty decided to try his hand in Europe in 1980, so the Pitmans squad remained largely under wraps. The face of racing in Australia was changing too, with the big, bellowing and spectacular Superbikes – largely home-brewed specials – emerging as the next big thing over the traditional grand prix classes. When Pretty returned and faced the prospect of spending the 1981 season at home, he wanted to be part of that scene too. His problem was that Pitmans, and Yamaha, had nothing suitable for the class. Or did they? Mal Pitman was one person who was convinced that the XS1100 could be made competitive in the Superbike class – but with one major modification. “Because of (our experience with the model) and our connection to the factory, Yamaha decided to make some factory engine kits for the XS1100 to allow them to go Superbike racing. Unfortunately they felt the shaft drive was suitable for Superbike racing, and I didn’t think it was, so they forwarded the bits to my father and uncles who ran Yamaha Pitmans and said they’d really like us to build a Superbike. My uncles basically told them what I’d said; that shaft drive was a waste of time. But they said, ‘you have to build it for us because we want to get the coverage’, so I elected to modify the bike to turn it into a chain drive XS11, and once I’d done that it made the kit come to life because you had less weight, you could change the gearing, and so then we were able to get racing. I had a local guy who loved bikes, was a machinist and dabbled with casting, and I showed him the problem
“Pretty and the XS1100 instantly became the major force in the 1978 Production Racing season, winning the prestigious Advertiser Three Hour in April, and two weeks later, the Perth Four Hour, this time paired with Mick Cole.”
we had with the right angle drive. We worked out that the shaft inside the right angle drive had the same spline as a TZ750 sprocket, so we proceeded to pull the shaft apart, cut the box up, we made an extension off the gear cover on the left hand side so it had an outrigger bearing, so we used the original shaft with two new housings and that gave us the sprocket on the engine. Then I had to build a swing arm for it that was wide enough, because we had to run the sprocket very wide, to miss the gearbox. That was made out of chrome moly, super strong, and we then ran TZ Dymag magnesium wheels – or the spoked wheels, depending on the weather. The rear shocks are the aluminium body and finned Koni 76V shocks, 5-position adjustable internally, which you did by taking the spring off and pushing the shaft to the bottom to adjust the internal damping mechanism for rebound and compression.
“It (the factory kit) was a very comprehensive kit. Crankshaft, con rods, pistons, a twin-plug head, camshafts, exhaust system, carburettors, hydraulic clutch, clutch springs, magnesium oil filter cover. The twin plug head Yamaha partly made with their Toyota 2000GT technology. It was an all-new head with 10mm plugs, the original plug was 14mm. Two plugs were side by side but you had to run each from a different ignition system. They supplied side draft Mikuni/Solex carbs, 40mm, sleeved back to 36 with the effective venturi 34mm. They had big long bell mouths, and long intakes like a 6 or 4 cylinder car, under-bucket shims in the head. I ran 11.5:1 compression, 100 octane fuel, two base gaskets to get the correct compression, XJ650 ignition as per factory spec. For Oran Park and Bathurst we had a small single phase generator on it with total loss for the last race. The race crank was a couple of kg lighter, with special con rods, and bigger con rod bolts. Forged high comp pistons, very thin 1mm compression rings, standard oil rings. The kit came with Mikuni/Solex Weber style carbs, they worked quite well but the bike was very hard to start. I didn’t want to run them because on that type of carb the float runs side to side so when you turn a left corner it leans off and when you turn a right corner it richens up. For me that was a big problem but Greg was happy to run that at Bathurst and we had no problems. Because we were running a TZ750 countershaft sprocket we had to change the middle gear (primary?) so Yamaha calculated what we needed and made me a set of new middle gears, I told them first gear was too low so they made me a high ratio first gear to make the gearbox a bit closer, but apart from that the gearbox was standard. Part of the factory kit was a bigger oil cooler. It got very hot if you idled it but in operation it was OK. It was still 1100cc standard so had plenty of fin area. Brakes had to be standard from the era, but in the day Yamaha brakes were the preferred brakes because they were 300mm, Suzuki and Kawasaki were only 280. They’re terrible now but in the day, they worked very well.
“We had planned to race the Superbike at the Coca Cola 800 at Oran Park, which was an 8 Hour race in February 1981. We were still building the bike as we were travelling to Sydney because it was such a big undertaking. Gary Coleman was the co rider. On the first day, he jumped on and did half a dozen laps and came in and said, “We’re going to win the race, no problem’. I didn’t believe him but he was quite sure. Then it rained and we won the race by seven laps, but Gary said the bike was so rider-friendly and easy to ride that we just walked away. “We then decided we would run at Bathurst in April, so we had a TZ750, TZ500 and the XS1100 for Greg to ride. Unfortunately at Bathurst there was only one practice session for all those bikes, so Greg had to go out and do two laps on one, come in, two laps on the next one and so on. It was the first time we had run the TZ500 and I hadn’t had a chance to do the jetting on it and it was jetted way too rich and even though I put 30 litres of fuel in it he ran out of fuel on the last lap when he was second. But he won on the 750 and in the Arai 500 he rode the XS and won by about a lap and that became folklore because it was a legendary bike that had a 100% winning record.” All change That could have been the end of the story for the chain-drive XS1100, but Yamaha Pitmans allowed Pretty to take it to Winton in Victoria for the opening round of the NGK Superbike Series in May 1981, along with a mechanic. However Pretty failed to make it to the grid after stepping off the Yamaha during practice, damaging it too extensively to make the race. The bike went back to Adelaide with immediate plans for a further outing. That matter was settled when Pretty dropped a bombshell by taking up an offer to join Team Honda, whose lead rider Dennis Neill had suffered career-ending injuries at Bathurst. It was a move that floored Pitmans, and severely cooled their enthusiasm for racing. In fact, it was just a further element in a chain of events that would change the company’s traditional business role, as Mal Pitman explains. “So we lost Greg, and the next year the government devalued the Australian dollar. We were importers so the family business decided we had to get rid of our race bikes, so they were all sold off. I had a guy, Colin Dymock, who used to come through each year when he was on holidays and he would always ask me if he could buy the XS1100 Superbike. I said it wasn’t for sale but about the third or fourth time he came through I said I’d sell it to him. He had eleven XS1100s so he had serious issues! He took it away and gave me his phone numbers at home and at work and I said if you ever want to sell it let me know. I rang up about five or six years later but both numbers had changed, so I lost contact and the bike basically disappeared for about 35 years, but he never told anyone he had it. “Then John Testore, who had worked for the NSW Yamaha distributors, McCulloch and used to service Colin’s XS1100s, was talking to him. Colin had become quite ill and was having trouble walking, so he took John down to his garden shed and said to him, ‘I’ve got the Yamaha Pitmans XS1100 chaindrive’, and John said ‘no way’, so he told him to go into the shed and look for himself. Unfortunately the roof had fallen in on the shed so the bike was badly weathered, but John knew straight away what it was and bought it from Colin and promptly rang me up and told me had had the bike. I kept that in the back of my mind and I was pretty keen to buy it because I’d always wanted to own it from back in the day. “Then in December 2017 PCRC rang me up and said they were having this 30 Years Celebration of Superbikes at the International Festival of Speed in March and could you bring the chain-drive XS? So I rang John and he said ‘I was going to ring you, I am pretty keen to get the thing restored’. So he brought the bike to the Australian Historic titles in 2017 at Goulburn and I took it back to Adelaide and got to work on the bike. It was a very tight schedule; it was only finished on the Tuesday of the week of IFoS. It’s not completely finished to my satisfaction but it has come up very nice although the carburation needs sorting out. A rapid restoration With scarcely three months to completely restore the bike, Mal Pitman had his work cut out, but despite the bike’s enforced hibernation, the task was not quite as daunting as it could have been. “The exhaust valves were stuck open and two of the
pistons had some moisture damage but I was able to get CRC into the motor and move it backwards and forwards until I could get it to turn over. I wanted to check the cam timing just to refresh my memory. So I pulled it all apart and it was still in really good order inside. I replaced all the main bearings and big end bearings, honed the bores, ran the same pistons and rings because they were in good order, cleaned the valves and recut the seats, re-shimmed it, put a brand new set of Keihin CR33 smooth bore carbs on it, fired it up and she ran sweet as. It was John Testore’s decision to fit the Keihins, but the original Solex/Mikuni carbs were badly corroded and would have taken a lot of work to get them back into working order – more time than we had.
“I know the guy at the local trade school so I put it on their dyno. This was the Tuesday night before IFoS and we had to leave at 3am on Wednesday morning.He said it was a bit lean at idle, too rich in the bottom range, nice at three-quarter throttle and probably a jet size out on the main jet. He said the torque curve is a flat line; it’s incredible how much torque it’s got. It was showing 108kW, or about 144 horsepower, and that blew me away because we always thought it was about 120 horsepower, but in those days we didn’t have dynos – we’d just ride it and see how it went. We were pretty impressed back then because it was as fast as Robbie Phillis’ GSX1100 and as fast as the CB1100R that Dennis Neill rode, which had a factory Honda RC kit on it. But Honda and Suzuki Yoshimura had all the experience whereas Yamaha had no four stroke experience. The next model they brought out was the FJ1100 which chassis wise were not great but the motors were bulletproof and great for making horsepower, and from there to the FZR1000. So this bike was the stepping stone and probably the first Superbike from Yamaha anywhere in the world. I know Sonauto had the Fior one (also chain drive which raced at the Bol d’Or) which had the same race kit on it but we basically raced ours as a full Superbike. All the cycle parts are standard – heavy steel fuel tank. I reckon the bike now is around 200 kilos and I think it could lose another 15kg by doing lots of little stuff. A quick squirt At Sydney Motor Sport Park, I was able to get a run on the XS1100 during one of the IFoS Legends sessions. After doing the earlier session on Murray Kahler’s NCR Ducati that I had raced in the 1978 TT, jumping onto the Yamaha was quite a contrast; one low and long, and the other bike high, wide and handsome. Mal Pitman’s son in law Nathaniel Wilson had taken the Yamaha out for a shake down run and reported fluffy carburation, so there was a quick hunt through the pits for alternative jetting prior to my ride. This went part of the way to curing the problem but Mal says he’s still not entirely happy with it, although considering the short space of time he had to complete the work, it’s a job very well done. Look at the period photos of Greg Pretty and you will see a little bloke on a big bike. The power-toweight ratio was very good. When I hopped aboard the XS I was immediately struck with the sheer presence of the machine. It’s not just that it is physically large, but the styling, especially the fuel tank, make it appear that way. Nevertheless, once you’re underway this impression disappears. What takes over is the stonking mid-range surge of power, and the overall performance package which, for a machine originally conceived over 40 years ago, is mighty impressive. From my lofty perch it seemed a long way down to the track, but the XS steers perfectly, and even though I had been pre-warned about the efficiency of the brakes, I found very little lacking there. I definitely agree with Mal that Yamaha had the pick of the brakes back then; even my own 1973 TX750 with its single disc, twin piston caliper stopped quite adequately, and I never had any complaints about the range of TZ350s, similarly equipped, that I raced in period. You do notice the weight, no question, particularly at the downhill hairpin at SMSP, where the force of gravity, coupled with a tight, decreasing radius corner, makes changing direction a considered exercise. But then comes the good bit, accelerating away towards Turn 11 and the Yamaha fairly bolts, with plenty of time between gear changes to savour the experience. As Mal says, the carburation is not yet spot-on, but it’s not all that bad either. Hey, let’s put the Solex/Mikunis back on and try that!
It would be an interesting exercise if Mal could indeed remove another 15kg, but in a way, I hope he doesn’t. Here is a time-warm motorcycle, pretty much exactly as it was raced in 1981. Even the paintwork is original. Yes, true – it only required buffing, even after all those years semi-submerged in the leaky shed. Thanks to owner John Testore for allowing me the chance to savour a real survivor of the battlefield that was the early ‘eighties Superbike scene.