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Dick Mann Lean angle

Discussion in 'Motorcycle Related Discussions' started by jseng1, Oct 23, 2019.

  1. acotrel

    acotrel

    Joined:
    Jun 30, 2012
    My friend owned the Egli TZ 750 which Goose Muir rode to a win in the Australian Swann Series in about 1978. I never rode the bike, however another close friend did. He said it was very torquey, however it made the end of the front straight at Calder Raceway look very narrow. As far as I know, the TZ700 had reed valves, as did the TZ750. I think the difference was a slight increase in bore size. The TZ700 had dual rear shocks, the TZ750 was monoshock ? Another friend was sponsored on a TZ700. I was told that he had tried the bike with two TZ350 barrels fitted, however when I asked him about that, he denied it had ever happened. When you think about it, that combination would be horrendous. A TZ350 usually has nothing under 8000 RPM, then you get everything. Apparently the TZ750 is very easy to ride. It would make sense if the very first TZ700 was piston ported, but I don't think that is what we had in Australia, and back then we got most things first.
     
  2. acotrel

    acotrel

    Joined:
    Jun 30, 2012
    I recently had a very respectable TZ350G which I sold to buy the 6 speed TTI box for the Seeley. It was a conscious decision. When TZ350s were raced in the 1970s, everything you fixed cost $1000. Modern historic racing does not justify that sort of expense. As far as fun is concerned the Seeley Commando is a much better option. These days, when TZ350s are raced, they are usually mixed up with four cylinder superbikes - silly stuff. There is only one guy in Victoria who has a TZ750 - he doesn't know how to use it.
     
  3. lcrken

    lcrken VIP MEMBER

    Joined:
    Mar 15, 2009
    Pretty close. The TZ700/750 was derived from the YZR500 racer. At their introduction, their real displacement was only 700 cc, so they were frequently referred to as TZ700s, but they were officially cataloged by Yamaha as TZ750 right from the start. They expanded it to 748 cc in 1974 by increasing the stroke. All of them had reed valves. The early production TZ750s were twin shock, but the works YZR750 had a monoshock. In 1976 Yamaha came out with the final version of the TZ750 line, the OW31. It had a number of updates and improvements, including monoshock rear suspension. In 1977 Yamaha did a limited run of OW31 replicas, calling the works machines OW310s. I think they only made 50 or 60 of them. It looks like they continued making the TZ750 through 1979, with the 1977 model being the TZ750D. That's what I had, and that was the year Yamaha changed it from twin shocks to monoshock I don't know much history on it, except that it had been raced by Jimmy Felice. I'm sure there's lots more info available with few simple on-line searches for anyone who's really interested. I get a little confused on the terminology between TZ750 and OW31 replicas, but I don't think it much matters unless you're a collector looking for authentification.

    Ken
     
  4. Bernhard

    Bernhard

    Joined:
    Apr 20, 2011

    Pretty close. The TZ 700 was actually at 698cc as it had two TZ350 piston ported barrels NO reed blocks were fitted. The TZ750 was a different bike altogether it was bored out to a pair of 375cc cyl blocks fitted, these barrels can be fitted to a piston ported TZ350 if the crankcase is opened up to fit.

    Actorel, Yamaha never made a reed block TZ700/698CC this bike was an update (at the time) of a 500 racing bike like the one Kenny Roberts won the 500 world championship on - you might have seen one with a pair of LC350 barrels fitted that’s still a 700/698- you might have seen a twin shock TZ700 with a TZ750 engine in it-I don't know what you saw- they have been used on world record attempts with a 350 and 250 barrels on it just to claim a 600 cc record in the 1970s!!!
     
    Last edited: Nov 8, 2019
  5. lcrken

    lcrken VIP MEMBER

    Joined:
    Mar 15, 2009
    Pretty close:). Not meaning to dispute you, Bernhard. I'm used to the stuff you post as being very reliable. Maybe we are talking about two different bikes? So I'll just summarize what I think I know about the subject. Feel free to correct me.

    I'm talking about the bike Yamaha developed as a factory Production 750 cc racer. The development was done in 1973, and I think the first customer bikes were produced in 1974, but I'm not completely sure about that timeline. It was developed by the same team, headed by Naito, responsible for the development of the YZR500, and was very similar to it, but with a bigger bore. The YZR500 was basically two doubled up 250 engines, with 54 x 54 mm bore and stroke. And it had Yamaha's new seven port "torque induction system", which had reed valves in the intake circuit. For the TZ700 they increased the bore to 64 mm, with the stroke kept at 54 mm, giving 695 cc. It was very similar to two TZ350350 engines doubled up, but in reality some of the major parts (crankshaft, piston, etc.) were not interchangeable with the TZ350 parts. But it still had the seven port, reed valve induction design. That was the bike Yamaha introduced as the TZ750A in 1974, and what I have been calling a TZ700. For the 1975 season they increased the displacement to 748 cc by increasing the bore to 66.4 mm. There might be some confusion here. The OW31 entries for Daytona F750 in 1976 were listed as 66 x 54 mm and 739 cc. I'm pretty sure someone just rounded the 66.4 mm bore spec down to 66 mm. All the TZ750 specs I've seen, except for the A version, list the bore as 66.4 mm.

    There was at least one TZ700 prototype, and maybe more, built in 1972 or 1973, called the OW19, but it also had reed valves. After extensive testing with Kel Carruthers, they made some significant chassis design changes, and the resulting bike debuted as the TZ750A at Daytona in 1974.

    There might have been other prototypes without reed valves, but I've never seen any reference to them.

    My major sources for this info is "The Yamaha Legend" by Ted Mcauley, published in 1979, ISBN 0 85614 057 0, a couple of articles by Kevin Cameron, several other period magazine articles, the 1976/77 issue of Motocourse, a little bit of personal recollection, and, of course, whatever I could find on-line that I could trust. I found plenty of on-line stuff that was incorrect, too.

    One of the best summaries of TZ750 history I found on-line is this one

    https://classic-motorbikes.net/99/

    And this one has a bit more info on the OW19 developing into the TZ750A.

    http://www.95customs.com/the-1974-80-yamaha-tz750/2015/2/24

    Ken
     
    Last edited: Nov 8, 2019
  6. acotrel

    acotrel

    Joined:
    Jun 30, 2012
    I had 4 friends who raced TZ700 or TZ750 - Doug Sharo who went to Europe. Greame Muir who won the round of the Swann Series. And Bob Rosenthal who worked for Milledge Bros in Melbourne. And Greg Johnston who rode Jack Walter's bike. When I spoke to Bob recently, I mentioned him riding the TZ750. He corrected me and said it was a TZ700. So I probably never really knew the difference. All I knew was they were the fastest thing unhung. Greg Donaldson was at Phillip Island with Ron Angel and they had the barrels off the TZ750 in a bucket of kero, using emery paper to remove the bits of aluminium. During a race, the motor rattled - but because Greg was in front he kept going. The motor chucked a rod when the bike was at full speed halfway down the front straight. Greg slid down the road at horrible speed and bounced off the guard rail. I watched it on TV and thought he was dead. He was out in the next race on a different bike.

    I have never had the ambition to ride anything like that. At least a Commando engined bike is relatively sane. And let's be honest, most guys cannot even use a 500cc Manx Norton properly. So why are we talking about 750cc two-strokes ?
     
    Last edited: Nov 8, 2019
  7. Time Warp

    Time Warp .......back to the 70's. VIP MEMBER

    Joined:
    Dec 3, 2012
    Which reminds me if the Sheene Akai TZ (practise bike iirc) is still gathering dust in NZ since the 1980's........... but I said that before today.

    #
    Motorcycles are not all about rip, $hit and bust, flaming cartwheels or chaos in general.
    I think you need a ride in the country (yes on the road) the sound of the engine disappearing on the wind and in no real hurry, you might be surprised.
     
    Last edited: Nov 8, 2019
  8. gortnipper

    gortnipper VIP MEMBER

    Joined:
    Nov 11, 2013
    Ah yes. Yesterday's Ton in the Sun on the on the Kaipara Coast on the Duc...
     
  9. acotrel

    acotrel

    Joined:
    Jun 30, 2012
    A lot depends on your own mentality. There is a group of former top A graders who go out for Sunday rides around Warburton near Melbourne. You would have to be insane to go with them, it is all about out-braking one another on roads which are surrounded by trees and drops. I rode on public roads until I was 28, then got sensible and went racing with a relatively slow bike.
     
  10. Time Warp

    Time Warp .......back to the 70's. VIP MEMBER

    Joined:
    Dec 3, 2012
    That is a great area to ride.

    The A man needs to get a bike together, the Ton Up ride is on the agenda for next year, one rule being bike and rider age needs to be 100 years or more combined.
    2000 kms to the start line for me and then 6500 kms back to home over the top, the annual Sunbeam rally is not long after and 2400 kms return which I would like to do also preferably not being run over by a B Double in transit.
     
  11. Time Warp

    Time Warp .......back to the 70's. VIP MEMBER

    Joined:
    Dec 3, 2012
    We have all been there, I used to go on a few organised rides (NZ & TL1000) guys doing 200 kmh wheelies etc... black lines in and out of corners I would go in the second group and you would only be 3 or 4 minutes behind at the next stop while enjoying yourself.
    To some degree it was inevitable, one ride I elected to not go for whatever reason, two died (GSXR1000's) both aged 26, that was some time now.

    But that has little to do with the enjoyment that can be had in a more relaxed social or not (solo) manner... but to not know it is to not perceive it.
     
  12. gortnipper

    gortnipper VIP MEMBER

    Joined:
    Nov 11, 2013
    101 years for me and Muttster this year.
     
  13. lcrken

    lcrken VIP MEMBER

    Joined:
    Mar 15, 2009
    That sounds like great fun, but a little far for me to make it:D. With my MK3 my total would be 121 this year.

    Ken
     
    Craig and Time Warp like this.
  14. Time Warp

    Time Warp .......back to the 70's. VIP MEMBER

    Joined:
    Dec 3, 2012
    I will be a spring chicken for that one at 107/108 for anything I would be prepared to take that distance based on past rides.
    At this point it would be the Eldorado which should be able to that distance easily (stopping might be something else) ... Based off FB there will be quite a few Commando's also (but we won't go there :D)
     
    Craig likes this.
  15. ashman

    ashman

    Joined:
    Jul 11, 2010
    Sounds like my mates and myself on our Sunday rides, we have been riding together for over 45 years now and its always a race to the first tight twisties up on the ranges, as long as they are having fun who cares what others think.
    Al I think it was sensible for you to stop riding on public roads at 28, getting out of our way was the best thing you could have done, but we also have mates who just cruise along at their own pace we always stop to wait for them at our next turn off and of course we all know where we are heading anyway, it also blows a lot of new comers who come for a ride with us, us old geezers who are still pushing their bikes to the limits and cranking them over to the edge of their tyres, we do have lots of fun together, we are always putting sh.t on each other and if you make a mistake don't they let you know about it, well that's what mates are for.

    Ashley
     
  16. ashman

    ashman

    Joined:
    Jul 11, 2010
    Not sure what class/age I would fit in on that ride 1957 Featherbed/1974 Commando motor and I am 61 next week, still over the ton anyway.

    Ashley
     
  17. Bernhard

    Bernhard

    Joined:
    Apr 20, 2011
    Re; “Maybe we are talking about two different bikes?

    frequently referred to as TZ700s, but they were officially cataloged by Yamaha as TZ750 right from the start.

    They expanded it to 748 cc in 1974 by increasing the stroke.

    All of them had reed valves.”

    The TZ range in the 1970s more or less until they changed them, all had 54mm stroke at one time, the 700 were made from the 500 GP racer at the time but fitted with 38mm carbs -later reduced for the reed block 750s to make them more rider friendly. There was a lot of mix and match of parts barrels, I have had a 350LC with a 350 TZ barrels on, seen a TZ350 with TZ 750 barrels on, (for someone who wanted to race at clubman level in the 500 class.


    https://en.wikipedia.org/wiki/Yamaha_TZ750

    https://www.carolenash.com/insidebikes/reviews/yamaha/yamaha-tz750/

    tz 350;

    http://www.tz350.net/tz350page.htm
     
  18. freddie1105

    freddie1105

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    Oct 23, 2019
    [​IMG]
     
  19. freddie1105

    freddie1105

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    Oct 23, 2019
    paul smart. 1970
     
  20. freddie1105

    freddie1105

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    Oct 23, 2019
    i'll give this though. Saarinen was on a different level to everyone else at the time of his death. a bit special.
     

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