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Info Castrol 6 Hour Stories

Discussion in 'Motorcycle Racing and Track Days' started by maelstrom, Feb 21, 2020.

  1. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    Us oldies will remember well the Castrol 6 Hour production race. Which was the premier production race in the world. Having been an insider (I built the engine for the Oakhill/Robbins Ducati team in 1977), I have a few stories to tell and thought some might find it interesting. For the younger reader some background https://www.mcnews.com.au/six-hours-a-year/

    1977 BMW Win
    Yes, it is true. Now I don't know to what extent every team on the grid cheated but it went on. Some breaches were caught and some not.
    In 1975 Metzeler produced an 18" 'racing' tyre, the C7. It was standard fitment on that years Ducati Super Sport models. It was a damn fine tyre, despite what the 'experts' said about it, and we had them on our bike because they were long lasting, had good grip and an excellent profile. There was no 19" version of that tyre and the BMW in question runs a 19" front wheel. Behold:
    BMW_1977.jpg
    BMW_1977_Tyre.jpg C7.jpg
    I didn't even notice it myself until I saw the pic of the winning bike on the front cover of REVS magazine. Not that I am moaning because it will take me a while if I am to document all of our misdemeanors.
     
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    Last edited: Feb 26, 2020
  2. Murdo

    Murdo The Good Doctor Staff Member Premium Member Ride and Events Crew Contributing Member

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    Fond memories of the ride to Sydney on Saturday arvo, sleep on the ground with some Stones Green Ginger wine mixed with Vodka, hung over next day to get to track to watch some great riders in action and the mad 'race' home after the races to get back in time for a couple of hours sleep before work on Monday morning. Shame that it ended but politics and greed move things along.
     
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  3. gregt

    gregt Well-Known Member Premium Member

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    I never went - but my business partner rode a couple of times. RD Yamahas arranged via the NZ agents.
    They at least finished - i think a 4th in class was their best. Not bad for tourists, lol.

    His best story was the TX750 Yamahas. One of the years he rode was the year Yamaha decided to enter a fleet of them.
    They watched in amazement during practise as engines blew and were replaced from a seemingly unlimited supply...
    This had not gone un-noticed by what I think was the only private TX entry.
    Anyway, post-race in the bar, my partner ran into the TX privateers who were looking pretty happy.
    They cheerfully told him that, yes, they'd finished, and yes, Yamaha had bought the bike out of the finishers enclosure - to find out why it was the only TX finisher...
    They admitted they'd never gone over 5000RPM the whole weekend.
     
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  4. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    Yes, sadly the TX turned out to be a bit of a lemon.
     
  5. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    Production Race? Forgive me father for I have sinned (Part 1)
    Everything that rotates inside an engine requires energy to make it rotate. Everything that rotates will also waste more energy if it is out of balance. So you lighten and balance everything that you can. Now with a 'production' engine you can't go sticking great big holes in things or the scrutineers will joyously find you guilty as charged, so sections are narrowed on the obscured side etc. I didn't lighten the crankshaft, well not to any degree that was significant, but I had a custom crankpin made from Bohler steel, nitrided and precision ground. Didn't want the big end to let go like it had done for John Warrian, an event that had previously robbed him of victory in 1975. Problem is that after balancing there is a considerable amount of metal removed from the flywheels and it doesn't look very 'production'. In the olden days Ducati used to have a rough version of the colour codes you see on the Japanese cranks. When faced with a situation like this you do something so outrageously obvious that no one will think you did it because it is too obvious, so I just painted over the large areas of missing metal with red paint.
    When you race, the track determines how you set things up. Amaroo Park has the climb up the hill, so torque and reliability was my focus. Another issue is the tight nature of the circuit which is not suited to the slow steering of the bike, more on that later. Bill McDonald, team owner, had done all the planning, groundwork and testing to run cold fuel (packed in dry ice) so we only needed two fuel stops instead of three. He had the huge task of making it all happen as well as putting up the money. I had actually left my job at Fraser's Brisbane, but I stayed on to work solely on the 6 hour engine. Not only because I wanted to do it, but one of the riders, Dan Oakhill, was one of my best friend at the time.
    Bill always wanted to go over all the details of the engine, like most of us he just loved tinkering with engines, and we also discussed the suspension at length. Not only is it good to listen to someone else's ideas but just talking about what you are doing often makes things clearer in your own mind. I am not trying to blow my trumpet here. This was a pretty simple task, just make a strong engine that could do the work and try to make the bike as easy to ride as we could. The riders have to put in 6 hours so you don't want to make it any harder.

    If you find these old stories interesting then please give a thumbs up and I will keep writing. If it is just boring everyone then I will can it.
    Cheers
    Blair
     
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    Last edited: Feb 21, 2020
  6. Murdo

    Murdo The Good Doctor Staff Member Premium Member Ride and Events Crew Contributing Member

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    Love it. Please carry on. :thumb_ups:
     
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  7. Linkin

    Linkin The Apprentice Premium Member Dirty Wheel Club Contributing Member

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    As above, please continue
     
  8. Andych

    Andych Well-Known Member Premium Member

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    Definitely keep going Blair... I grew up a few streets away from the Willing Bros and a few mates ended up with "stock" bikes with Chesterfield barrels etc because of the Willings. Love all the insights.
     
  9. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    Part 2
    Ducati 750 SS - 900 SS Owners Handbook - 6 Hour Edition

    I didn't have any part in this shenanigans but funny story anyway. As some of you may know the early Ducati Super Sport models were based on the bike that won the Imola 200 in 1972. In fact the round case models were as good as identical. The factory offered race kits for these bikes, which included the now famous Imola camshafts, upswept pipes, full racing fairing and oil cooler. The details of the race kit, including the timing specs for these cams, were included in the owners handbook.

    For the 1976 6 hour race, Peter Lane entered a 900SS that was ridden to 3rd place by Dan Oakhill & Ross Pink. Dan was leading the race for quite some time but the rear tyre was down to nothing when he took over for the final hour. Anyway this engine was fitted with Imola cams. To keep the scrutineers happy they gave them a handbook that had the original section on cam timing specifications replaced with new pages showing only the numbers for the Imola cams. I found a carton of these handbooks tucked away above the workshop in Brisbane. Years later the inserted pages faded to a darker shade than the others so the '6 Hour Handbooks' are readily identified. Wish I had them now, I could sell them on eBay.

    For all this chicanery, little was achieved. Why, because the ports on the bevel drive V twins are complete rubbish. The Imola cams worked brilliantly on the 750cc engine because they only kicked in hard around 7000rpm. From there to 10000 the 750 screamed as it was meant to. Putting these cams in the 900 (which is actually 860cc) is pointless. Both engines share the same cylinder heads including valve sizes and carburettors, so the larger engine is incapable of filling the cylinders at higher rpm. Speaking of ports. The engine that I used was one that was sourced from a wreck and had no front cylinder head. I took a brand new head from the parts shelf and, cross my heart, did not do a damn thing to it. These heads are sand cast they are never going to all be identical. Well the scrutineers used a burette to cc the port volumes. All of the Ducatis had different results but ours was the largest, so they said we had to replace the front cylinder head. In other words, the only discretion that they found was a nothingburger. You couldn't make this stuff up.

    For the 1977 race I used the standard cams but unfortunately Bill had brought a '6 Hour Handbook' with him to give to the scrutineers. What a debacle! The numpties knew enough to understand that the measurements they were getting from the standard cams were milder than the specs in the book. Maybe they were happy with that. I wanted nothing to do with it as I had already crossed paths with the chief scrutineer, Chris Peckham. When we arrived at the track he couldn't wait to greet us and tell us how he didn't want Ducati's in the 6 hour because they were not touring bikes. I responded that just because i don't carry tea bags in my panniers doesn't mean I cant ride a sports bike on the road and it escalated quite quickly after that. Bill had to calm down the situation. But wait there is more, Ian Gowanloch, some of you might know that name, was my counterpart but in the Sydney branch of Frasers at the time. He had prepped their entry and after prodding the kickstart on his bike. I commented about the lack of compression. Years later Ian told me that he had used the race cams and also had the matching 'special' handbook. God only knows how that nonsense ever got through scrutineering. In any case our bike was on equal pole for the race so job done.

    HandbookSmall.jpg
    As close to the correct version as I could find on the web of things.
     
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    Last edited: Mar 14, 2020
  10. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    Good stuff, was always an admirer of Warren. Shared the starting grid with him and Greg Hansford once at Lakeside when they wheeled their 750s off the track in protest at the push start.
     
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  11. Bob Sykes

    Bob Sykes Well-Known Member

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    Good stories, love ‘em, keep them coming. I went to a few at Amaroo and Oran Park. Flagged in ‘84.
     
  12. gregt

    gregt Well-Known Member Premium Member

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    "Chesterfield barrels" amuse me. A local dealership ran a pair of RD250's in NZ 250 production. Successfully too.
    It's interesting to note that Dymo tape labels have exactly the same size and shape as the cast in capacity labelling on Yamaha barrels...
    I happened to be in the shop one day and saw a set of barrels I wasn't meant to and commented that they were a tad bigger in the bore that I expected, LOL.

    Both the lead rider - a very well known international long since retired now - and the mechanic responsible live in Aussie now.
     
  13. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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    Love it, continue please
     
  14. Murdo

    Murdo The Good Doctor Staff Member Premium Member Ride and Events Crew Contributing Member

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    When we had the 250cc rego rort going on I used a small piece of copper wire to form a '2' , filed off the '3' from a set of 350 barrels and glued the '2' on with araldite epoxy and a squirt of black paint. Fastest 250 around for a while. :D
     
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  15. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    Shocking! (Part 3)
    As I mentioned earlier, the Ducati SS is a very slow turner. 1.5 metre wheelbase and lots of trail means it loves high speed rolling curves and is useless on goat tracks. Another issue faced by everyone at a race track is ground clearance, which just seems to vanish when you use a ’70’s road bike. The SS sits very low as it is, and the early models had the shortest suspension of the range. To deal with that I lengthened the rear shock by 15mm, and as I recall, Bill did the front by about 5-10 by using stanchions from another model. The standard rear shock (Marzocchi A73) is a dead simple piece of equipment, easily rebuildable and lots of interchangeable parts. I stripped a set of shocks from three different models, an 860, a GT and the SS as I recall, and just swapped parts around to get the desired result. We could have done any manner of tuning adjustments but we stuck to the basics. Without having easy access to Amaroo it was pointless.

    When it came time for bike measurement at scrutineering. We wheeled the bike in and hit the front brake to cause the front to dive and one of the guys put all his weight on the seat hump to keep the back down (he was just steadying the bike :)). The scrutineers measured the seat height and compared it to the handbook "Yes, all good". Our shocks were so long that you could just glance at a standard set on another Ducati and the difference would poke your eye out, but there you have it.
    A73Small.jpg
    This is not the Ducati SS shock but it is an A73. They don't make them anymore, shame.
     
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    Last edited: Feb 22, 2020
  16. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    Journalists & Dry Ice:
    Well lots of nonsense floats around about how in 1977 the BMW ridden by Eastmure & Blake pulled it off and that the BMWs only needed 2 fuel stops. False. The winning team only needed two stops because for their final stop they used fuel that had been chilled with dry ice (-78C) by our team. We didn't need it anymore since Dan had crashed and the dream was over, so we might as well spoil the Kawasaki party. The Hatton/Dahne team had to shoot into the pits for a final top up and finished 5th, but the Eastmure/Dahne team did not. This photo from a book by Ian Faloon but originally sourced from Two Wheels magazine gets it all wrong. The BMW team were not that stupid to waste time with a drink bottle. This was a quick patch because nobody knew how much we could stuff into the BMW tank.
    Fuel.jpg
    FuelCaption.jpg
    You can see this is not adding 50ml. The bottle is still more than half full. The BMW team would never be this pathetic. The Kawasaki team a year earlier had filled their tank in 6.5 seconds. Do you think they will stand around with a whiskey bottle of fuel? Notice the tank starting to freeze up. The guy with the hat was from our team and the one with the bottle is Paul Trenkner, also from our team. The dodgy piece of foam is also from our team, we used to throw it at each other and refer to it as apiece of hi-tech equipment. You would think that any journalist with half a brain would want to dig a bit deeper and find out what the hell is going on. I am not in this pic because my job in the pit was changing the rear wheel of a long since crashed bike.

    If you really believe that this is the BMW modus operandi then here is a pic from 1976
    1976BMW.jpg
    i saw an article where Joe was interviewed and he said "oh yes we used chilled fuel like we always did" pffft
     
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    Last edited: Feb 26, 2020
  17. gregt

    gregt Well-Known Member Premium Member

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    Ah, ground clearance, LOL. Always the biggest problem racing proddy bikes.
    Did you remake the front pipe on your Duc like some were ?
     
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  18. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    6 Hour Headers
    What @gregt said. Yes, both headers on the bike were modified so extensively that you could not access the lower cover screws. It was so blatantly obvious and yet the year before the scrutineer had taken issue with Peter Lane's entry (same 'special' headers fitted) because he discovered the number '8' was upside down. All Ducati pipes of that era had the part number stamped into the header with the '8' upside down. The headers were made by Brian Payne https://amcn.com.au/editorial/not-forgotten-brian-payne/. Thereafter I would make them for customers if they wanted and they were appropriately dubbed '6 Hour Headers' . I just used mandrel bends and a gas torch.
    header.jpg
    This is the standard front header and you can see the lower timing cover screws are accessible as opposed to completely covered on the 6 hour version. Sorry, no pics.
     
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    Last edited: Feb 23, 2020
  19. kiffsta

    kiffsta Administrator Staff Member Dirty Wheel Club Contributing Member

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    Coll stories Blair , there have been a few on this page too


    1A10AAD0-DE1A-4352-8862-868495C9C402.jpeg
     
  20. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    Cam Timing:
    Dinosaurs already know this but it seems we are dying out. In gear driven cams where there are multiple gears with different number of teeth you can advance or retard the cam timing. In the case of the square-case bevel drive Ducati engine this is dead easy. You wouldn't think so with all the numpties on the web of things advising each other to make offset woodruff keys to fit the camshaft drive gear to the camshaft. Just blows my mind. If you want to move the torque peak higher you retard and vice versa. So imagine Inlet Centre Maximum Lift (ICML) is 98° after ATDC and you want to tune this engine for high rpm then you will make the inlet cycle later, so maybe ICML at 104° deg after ATDC. I like to use ICML for cam timing because it has nothing to do with measuring clearances etc. This is for tuning not increasing performance. I use a degree wheel and a dial gauge to determine ICML not the 'just add this and this and divide by 2 method that you might find mentioned in various articles.
    Okay so here is what it looks like:
    Timing.jpg
    This is a spreadsheet and I have calculated the change per tooth for two separate gears. Move the distributor gear back 15t and the bevel gear forward 7t, done. This is so easy that I can do it in the pits. Mind you, zero margin for error or you can say goodbye to the engine. Not only did I do this for race bikes but also customer's road bikes, on request of course. These days I would have the gears laser marked to make this much easier.

    Still not very clear is it? Okay a pic is needed.
    Timing3.jpg

    So my arrows should be curving, but I think you can get it. You rotate one gear in one direction and the other gear in the opposite direction. The sum of the two (in timing degees not teeth) is how much you have altered the timing.

    Cheers
    Blair
     
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