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Thread: Race chassis

  1. #631
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    I agree, the first time it's cranked over and hits a bump will be interesting to say the least...

    I reckon he's seen a Britten or read a lot of articles on them at an impressionable age. He's even copied the features which gave problems...

  2. #632
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    Quote Originally Posted by Grumph View Post
    I agree, the first time it's cranked over and hits a bump will be interesting to say the least...

    I reckon he's seen a Britten or read a lot of articles on them at an impressionable age. He's even copied the features which gave problems...
    I seen the other day how they Fixed the chatter in one test of the Britten at either Mike Webs or Mike Sinclairs suggestion (I can't remember which), they bolted on a few KGs of lead as extra unsprung weight



    Kinky is using a feather. Perverted is using the whole chicken

  3. #633
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    Quote Originally Posted by husaberg View Post
    I seen the other day how they Fixed the chatter in one test of the Britten at either Mike Webs or Mike Sinclairs suggestion (I can't remember which), they bolted on a few KGs of lead as extra unsprung weight
    Probably Mike S. I'll ask him IF I remember, IF he ever rings me again..

    Remember, I'm the nasty scrutineer who made them put steering stops on it instead of using the damper as the stops...

  4. #634
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    Quote Originally Posted by Grumph View Post
    Probably Mike S. I'll ask him IF I remember, IF he ever rings me again..

    Remember, I'm the nasty scrutineer who made them put steering stops on it instead of using the damper as the stops...
    Pretty sure that one was actually clearly written in the actual rules.
    It used to read something like not relying on the circlip from memory. right back to the small ACU rule book days



    Kinky is using a feather. Perverted is using the whole chicken

  5. #635
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    If you go back to the early parts of this thread, there was mention of the Westoby's Rotax powered 125's and the frames they built.

    I happened to turn the TV on yesterday to a programme where the narrator was visiting Temuka and looking at the Richard Pearse flying history...They fired up the replica Pearse plane - and there was Lex Westoby. Fair enough, he built the replica motor.
    Fame at last...

  6. #636
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    Quote Originally Posted by Grumph View Post
    If you go back to the early parts of this thread, there was mention of the Westoby's Rotax powered 125's and the frames they built.

    I happened to turn the TV on yesterday to a programme where the narrator was visiting Temuka and looking at the Richard Pearse flying history...They fired up the replica Pearse plane - and there was Lex Westoby. Fair enough, he built the replica motor.
    Fame at last...
    http://www.kiwibiker.co.nz/forums/sh...post1130221509
    http://www.kiwibiker.co.nz/forums/sh...post1130224186

    Well over 200 people viewed the pics which by KB standards is a lot, as they had no cleavage.
    (I am not sure if this will work) but I have posted over 10,167 pics in KB

    http://www.kiwibiker.co.nz/forums/imgbrowser.php?
    Sorry the link didn't work.
    you need to click on husaberg above this post then view attachments by user, then set to, from the beginning, set the image finder to 70 per page, and by number of views.
    These Westoby pics I posted for you are ranked in the top 70 out of all the 10,167 pics I have ever posted.
    That's a lot of pics (thanks KB)



    Kinky is using a feather. Perverted is using the whole chicken

  7. #637
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    Dave Pearce @ Tigcraft sent me some photos of his latest project, a Moto3 bike powered by a Mahindra engine. He says it does 50bhp on the same dyno that shows a standard customer NSF250 Honda at 43. Weight is 82kg.

    cheers,
    Michael







  8. #638
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    wonder where you buy one of them engines
    i'm over buckets

  9. #639
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    I think Dave said it was factory/factory-supported team engine from a season or two ago.

    cheers,
    Michael

  10. #640
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    Nice!
    Always wondered two things:
    1) how people can build such beautiful projects with such hideously dirty and messy workshops. Probably because they're the type of people to just get on with it and make something rather than fuss about stuff like tidiness.
    2) if I (a total amateur racer) would be able to feel the handling differences from the short stumpy fuel tanks Moto3 bikes run now, vs. the older conventional style tanks of the Honda RS125 etc.

    Something to ponder at least.

  11. #641
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    Quote Originally Posted by chrisc View Post
    Nice!
    Always wondered two things:
    1) how people can build such beautiful projects with such hideously dirty and messy workshops. Probably because they're the type of people to just get on with it and make something rather than fuss about stuff like tidiness.
    2) if I (a total amateur racer) would be able to feel the handling differences from the short stumpy fuel tanks Moto3 bikes run now, vs. the older conventional style tanks of the Honda RS125 etc.

    Something to ponder at least.
    Tank
    I think you will fine it's a perceptive issue.
    Given the tank endpoint is behind the swingarm pivot; I think ouy will find they are about the same length.

    Clean workshop = - simple mind, anal retentiviness or lots of free time... You choose.

  12. #642
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    Quote Originally Posted by chrisc View Post
    Nice!
    Always wondered two things:
    1) how people can build such beautiful projects with such hideously dirty and messy workshops. Probably because they're the type of people to just get on with it and make something rather than fuss about stuff like tidiness.
    2) if I (a total amateur racer) would be able to feel the handling differences from the short stumpy fuel tanks Moto3 bikes run now, vs. the older conventional style tanks of the Honda RS125 etc.

    Something to ponder at least.
    Well, that's your invite to my workshop rescinded...unless you bring a brush and shovel.

    Any of the GPR frames ever used a tank dropped down in the frame ? Like a few guys used on ZXR400's and FZR 400's.
    I'm also contemplating a box structure steering head for direct input to the airbox. That tigcraft has given me ideas how to do it.

    I also note that Dave's seat subframes are getting stiffer. The sheet structure must be much stiffer than his earlier tubular versions.
    Can we assume that the rider's physical input was causing flex ? Shades of the bolted up vs welded up featherbed...

  13. #643
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    Dave told me several years ago that he hadn't made a tubular seat subframe (steel or aluminum) for quite a while. Instead he bends it up from 2mm 5083 sheet, welds where he needs welding, and that part of the bike is done.

    The folded aluminum sheet subframes are light, stiff, reliable and easy to make.

    That sounds like a good combination to me.

    cheers,
    Michael

  14. #644
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    Quote Originally Posted by Grumph View Post
    Well, that's your invite to my workshop rescinded...unless you bring a brush and shovel.
    It hardly bothers me that much, it's not me who has to make things in it! I'd happily come check out your dumping yard workshop.

    Quote Originally Posted by Bert View Post
    Tank
    I think you will fine it's a perceptive issue.
    Given the tank endpoint is behind the swingarm pivot; I think ouy will find they are about the same length.

    Clean workshop = - simple mind, anal retentiviness or lots of free time... You choose.
    Just to be clear: It's not the length I'm talking, it's the weight distribution. See the Moto3 'tanks' are actually 2 parts. Only the rear half is the fuel tank which is more vertically designed rather than horizontal. I'm sure the overall dimensions of the fuel tank, cover and air box would feel much the same as a conventional tank between the legs but the weight of the fuel being more rearward in the bike would have a handling effect. I'm wondering if even an amateur like myself would be able to notice it, or if it was one of those slight differences that only world championship level riders can pick up.

    In saying that, the Tigcraft tank looks two parts like a normal Moto3 but I can't see a filler so maybe the front half is the fuel tank?

    See moto3 tank here:

  15. #645
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    Dave sez:

    the chassis weighs 6kg bare which is about par for the class. I use one inch T45 17SWG tube Tig welded. The geometry is based on modern practice which means a higher swingarm pivot. The FG385 Moto3 Ohlins are about 40mm longer than the previous 125 GP Ohlins. The front part of the"Tank" is all airbox with a duct through the waisted headstock which doubles as the front fairing bracket. The tank is in the subframe.
    Another aspect I take a particular delight in is all this is done these days in my little shed with just a tube bender a small lathe and an inverter Tig plant. Not an android app in site.
    I respect the modern methods but I like being part of a vanishing breed.
    \

    The location of the tank has to do with mass centralization, as well as the steep downdraft angle on the intake making the front part of the "tank" a good spot for the airbox.

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