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Building the past

Discussion in 'Other 250's' started by gregt, Jun 3, 2021.

  1. gregt

    gregt Well-Known Member Premium Member

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    This is the current build. A late vintage Triumph 250 engine and box in what could have been built in the late 50's.
    Here in NZ from prewar to 1962 we had the NZ GP meeting on a closed public road circuit outside Christchurch at Cust. There were of course very few genuine roadrace machines in NZ in the 50's so a large number of specials were built. The 250 class was very popular with special builders as you'd expect. The L2/1 250 Triumph was a favourite among the builders as it was strong and could be tuned to make good HP. It's the 250 before Turner got his hands on the Triumph range and cheapened them. The L2/1 has full height barrel studs - Turner's Tiger 70 has a flange on the bottom of the barrel with short studs...
    This engine has recent race history. I built it up for a friend in a rigid frame with Cust history. He didn't like the way it handled so I've got hold of it. the rigid frame is going to another friend who has the 1949 250 GP winning L2/1 engine and box - but no frame.
    This is a copy of a Beasley frame of the period. Doug Beasley built quite a few Velocette 250's with this frame layout in the UK. One found it's way to Sydney and was copied in numbers there.
    I even have an alloy dustbin fairing for it. Which needs repair but it's there.
    Forks and front wheel are AMC. According to the part nos they are ex WD - which I'd call BS in NZ.
    We got whatever was available and laying around the factory. They'll do anyway.
    Oil tank to mock up next.
    I'm trying to do it as it could have been done in around 1957. I know that's the date of the fairing.
    It won't be highly finished as they never were. Cust had a fair amount of gravel....


    New build.JPG
     
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  2. Murdo

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

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    Sweeet!
     
  3. kiffsta

    kiffsta Administrator Staff Member Contributing Member Dirty Wheel Club

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    That is fantastic, kind a my dream build right there... 50’s bike with dustbin fairing , I just can’t find a donor bike

    cant wait to see what you do with it
     
  4. inchoate

    inchoate Member Premium Member

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    I’ve spent too much time around Phil Irving’s motors so those pushrods look hilariously long to me.

    Great project, can’t wait to see how it comes out.
     
  5. gregt

    gregt Well-Known Member Premium Member

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    You're not wrong, LOL. They are however aluminium tube. Modern springs and a very good cam form means it will rev to over 7 grand in moderate safety. the cam profile is actually Aermacchi N6 - which is the final profile used on what you'd know as CRTT engines. The 350 macchis with 80mm stroke - like this Triumph - we rev to 8500. But with Yamaha rods and bigends...

    In the rigid frame it was not slow. Part of the reason probably why the owner didn't like the handling.

    If you're familiar with Irving's engines, I'd better not tell you the dustbin is ex Bob Burns...It has an interesting history
     
    Last edited: Jun 4, 2021
  6. gregt

    gregt Well-Known Member Premium Member

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    Footrests and foot controls are made up. Footrests use Triumph period pillion footrest rubbers - worn of course. Pulled out of the rubber bits bin at the local Triumph restoration specialist. For some reason no-one wants worn ones, LOL.
    Made up the 2 pieces for the oil tank today. Bent up the top/back/bottom piece and still have to form the curved front/side piece.
    In keeping with the period style, I bought an old 5 gallon fuel can and will use the spout and brass cap as the filler neck and cap on this oil tank. It's a Lesco fuel can which I know was made in Christchurch around the period.
    Might get the last piece formed and the tank tacked up tomorrow. A local offroad car fabricator is going to TIG it for me in exchange for borrowing my tube bender to do some nerf bars....

    Then I've got to put this project aside and clear a couple of customer things out of the workshop.
     
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  7. gregt

    gregt Well-Known Member Premium Member

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    Back onto it in bursts. Tank is tacked up but the local guy who is going to TIG it was away at an off-road race at the weekend. In Nelson - where he got caught by flooding. I think he arrived back late today so i'll hit him up tomorrow.
    Making up all the bits and fittings for it is time consuming.

    There's a reed valve on top for the engine breather, so a cover and hose inlet for that.
    Return line fitting - a threaded boss - to go on the filler spout.Visible with the cap off.
    Feed line fitting - another threaded boss - to go on the bottom edge. It'll serve as the drain too.
    Tank breather separator chamber and hose fitting for the top.
    Two bottom mounts - one each side of the engine plates with urethane bushes and alloy centers.
    A top mount with a rubber bush - and the matching mount on the front seat mount channel.
    None will actually go on until it's TIG'd.

    Looking at the pipe and where I want it to go. A tight front bend and a swept back line. I'll have to get a 1 1/2in doughnut in order to make up the very tight first bend. It's effectively half of an early T100 twin - same bore and stroke - so the old favourite 29inches of plain pipe will work as it does on the twins. Silencing was already a simple 6in long slot on the pipe.
    It's legal for the Classic class here - and it wasn't particularly noisy.
     
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  8. gregt

    gregt Well-Known Member Premium Member

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    Pipe's tacked up. Still to do a single rear mount. It also has a clamp on the stub at the head. Two new bought bends, one from my scrap bin - and one from an old Vance and Hines Z1 header....Recycle, lol.
    Quite pleased with the line. Line of pipe.JPG
     
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  9. beano

    beano Well-Known Member Premium Member

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    Really liking the diversity of machines that's coming into the site lately, subscribed!
     

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