Vintage Motocross Triumph, Old Guy Build.

Discussion in 'Some Assembly Required' started by Nemosengineer, Sep 4, 2017.

  1. Nemosengineer

    Nemosengineer Hair Ball

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    So here we are... I just finished an extensive rebuild on my Super Glide and if I didn't find a new project I was afraid I would just rip it apart again... (Link: http://advrider.com/index.php?threads/harley-dual-sport-the-land-speed-street-bike.1051908/)
    This is the result of the Super Glide project.
    [​IMG]

    I have been looking for a wet frame Triumph for a while and I found the perfect kit bike on Ebay for a really good price, 1972 T120 Bonniville cases, frame, swingarm and title.
    [​IMG]

    So what are we building... Per AHRMA, "11.1.10 SPORTSMAN OPEN TWINS: Unit-construction or pre-unit, four-stroke motorcycles with two or more cylinders through the 1974 model year, and like-design machines, manufactured as 600cc and larger. No major components may be later than 1974, actual wheel travel is restricted to conform with the 7-inch/4-inch rule, Sportsman Open Twins have no displacement restrictions".
    What's the plan...
    The chassis needs to go together first, forks (7 inches of travel :1drink) and wheels will be 1973 ish Husqvarna 400CR (The CR rear hub has a full floating brake and the hubs are bomb proof and light), triple clamps will be custom because the early Husky stem doesn't play well with the Triumph steering head, as a bonus I can pull the fork legs 10mm closer to the stem so the bike will actually turn.
    The engine will be built as a long rod Morgo 750, early 9 bolt head with mild head work, JOMO 15 cams, dual 32mm VM Mikunis, and a 1978 5 speed transmission. Why such an odd combination...
    Easy I already have some of the parts.
    Photos will be posted as things get started and more parts start to arrive. While we are waiting here's some inspirational photos.

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    #1
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  2. dpforth

    dpforth no inline fours

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    I'm in. I have similar plans for a small block Guzzi, for a playbike. That first Norton is gorgeous.
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  3. invisa-bill

    invisa-bill Adventurer

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    Beautiful Glide! Love that Bitsa II.
    #3
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  4. motu

    motu Loose Pre Unit

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    That's how the Rickman brothers started out - putting T100's into BSA frames.
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  5. nickguzzi

    nickguzzi Long timer

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    Agree with dpforth, that Norton, or rather NorBsa, is spiffing and my personal favourite. Love the idea.
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  6. Nemosengineer

    Nemosengineer Hair Ball

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    Thanks everyone for the kind words. Junk is starting to show up, Things that arrived today are 1973 Husqvarna CR400 forks, and a CR250 wheel set with axles spacers and backing plates. Cosmetically fairly ratty but for the most part rebuildable, the only downside is I will need to get ahold of another rear hub as the brake surface is extremely worn, but it will work fine for fit up.
    The fork tubes are laser straight , the fork internals look nice and the action is smooth... Winner!!!
    The Husky rear hub uses 6302 RS wheel bearings (15mm X 42mm X 13mm) with a 15mm axle.
    The Triumph uses a 5/8" rear axle, so here is the math with everything converted to decimal...
    .6250 - .5905 = .0345, So the triumph axle is bigger and doesn't fit in the hole... currently I am looking at a bearing house that does "specials" from stock by ID grinding on cnc tools, so I can use the Triumph axle in the Husky hub with the help of franken bearings... Or not I have to talk to the bearing guy... More as it arrives.

    I know this looks fairly grim but its all 44 years old... The plan is fit parts and make pretty later.
    [​IMG]

    Caution: What is said here may not actually happen the way I said it would... Its an adventure...:jack

    : Mike
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  7. nickguzzi

    nickguzzi Long timer

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    If you need another hub, would one of the Triumph conical hubs work?

    If not, and you are wedded to the Husky hub idea, would boring the hub out to an imperial sized bearing work better. Any replacements - a distinct possibility - would be much easier/cheaper to source.
    #7
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  8. TUCKERS

    TUCKERS the famous james

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    Can you use a 1978 gearbox as per AHRMA?
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  9. Nemosengineer

    Nemosengineer Hair Ball

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    My only objection to the Triumph conical hubs is they weigh a ton, I went with the Husky hubs because their light and tough. The Husky hub situation is not as bad as it sounds as I found a 1973 bare replacement hub with a nice braking surface for $42.00 delivered, it should be here in a few days.
    I have made progress with the modified bearings, I have requested a quote from MRC Industrial Bearing Products (SKF), as they have a "made to order solutions" shop in house. The more likely candidate is the company that does machine tool bearing work for the company I work for, I have requested a quote from them also, so more news as I get it.
    Boring the hub for a imperial bearing would be a viable solution, but If I can get the bearings it makes my life simpler as all I have to do is drill and ream the internal hub spacers and fabricate 2 axle spacers and I'm done, plus I get to play with my lathe.

    Yes because the 5 speed was introduced in 1972 and per AHRMA... "Unit-construction or pre-unit, four-stroke motorcycles with two or more cylinders through the 1974 model year, and like-design machines". The 1978 transmission is functionally no different than the 1972 model, it has the same internal ratios, but better bearings and fifth gear set and other detail changes that fixed the reliability issues of the early models, this transmission change is a bolt in and falls under the "and like-design machines" clause.

    Thanks: Mike
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  10. villageidiot

    villageidiot Long timer

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    could you machine the axle down to 15mm except where it goes into a new made spacer and maybe make a special axle nut like that of a "mag lug" for the other end?

    or machine the axle, special spacers, and then plate the swingarm with a smaller slot on the other side?

    id just try to make it so that any wear items/replacement parts were easy and straight forward to source.
    #10
  11. Nemosengineer

    Nemosengineer Hair Ball

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    All in all a good day, through a friend I work with I was connected with a machine shop owner named Rod who does prototype work in the San Diego county area. Turns out Rod has an CNC I.D. grinder and agreed to do a sample bearing to see if he can do it, If all goes well Rod will do a run of 6 modified bearings for me. Rod has won himself a 18 year old bottle of scotch. Folks like this deserve to be treated well. WOOT...
    [​IMG]

    I came home to find a box on my porch with a new used Husqvarna rear hub in it. I lucked out, it's in really nice condition, no deep corrosion just a bit of surface rust that is cleaning off nicely with WD40, stainless steel welders brushes and scotchbrite. the braking surface is nice and square with very little wear.
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    A nice feature of the Husqvarna hubs is the double lip oil seals that seal on the OD of the axle spacers.
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    Ooh... A bonus, a sprocket with teeth on it.
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    : Mike
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  12. Nemosengineer

    Nemosengineer Hair Ball

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    Thanks for the ideas. Its a good backup plan in case my modified bearing scheme doesn't work out. The actual list of parts that get modified are the internal hub spacer the internal brake backing plate spacer, and the brass floater bushing for the backing plate. The amount of material that's being removed is less than .035 inches from the internal diameter of these parts so there's not that much work involved, if things go well I will have three sets of modified bearings in my hands in two weeks, or not we will see. Once I get the wheel in the swingarm that's where the real adventure begins as figuring out chain line and the lacing offset from factory is always really exciting.

    Best Wishes: Mike
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  13. villageidiot

    villageidiot Long timer

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    I built a bike for a friend, xt500, deraked frame, radian forks and swingarm, yz450 rear wheel, yz250 front wheel, disc brake front and rear, was a lot of spacer machining, stepped axle spacers to fit the hub bearing/axle etc.

    But it all worked without any wild CNC parts.

    I love the CNC grinders, I use a shop in orange, ca that does precision grinding. The possibilities are endless
    #13
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  14. Nemosengineer

    Nemosengineer Hair Ball

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    More parts are showing up, at this point I have really nice cases with all covers with exception of the primary cover, last edition five speed transmission with all the bits to keep it right hand shift, a perfect T140 crank, a stock bore T140 cylinder with tappet blocks, clutch complete, and most of the primary drive. I'm still looking for a T140 splayed port Bonneville head, rocker boxes, and rods. Photos will follow in a few days, I am currently deburring the cases as finish work is something that Triumph did not do, handling the bare cases is like handling razor blades, this should be done in about a week I hope.
    On a more cosmetic note... I found my alloy fuel tank in reasonable condition, I will have the kinks worked out and the tank will be polished in the future. This tank was used on a few different models of Triumphs and differed only in paint jobs and the number of petcocks.

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    This seems to be the look I'm going for, pretend there's a T140 engine in there.
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    I'm looking for a dirt track primary cover, If anyone has one laying around :-).
    [​IMG]

    : Mike
    #14
  15. villageidiot

    villageidiot Long timer

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    if looking for dirt track parts, maybe post a "want ad" on vft.org lots of people look at that.

    as for the head and parts you're looking for, try classic cycle in orange, CA they do mostly british, and seemingly a lot of it.

    also triumph classic motorcycles in costa mesa, CA
    #15
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  16. tinwelp

    tinwelp Professional Idiot

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    Too late I guess, but 16x42x13 bearings are readily available in Europe. As 5/8" is 15.89mm you may get away with the additional clearance on the bore using the Triumph axle. Simple and cheap... but if you've already got your custom-made bearings, too late!

    Cheers... Paul
    #16
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  17. Beezer

    Beezer Long timer

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    I never worked on the "new" ones but I know that Triumph switched the gear shifter to the right side in '76... dunno how that affects the gear box. looks like you have all the major components already, but the wet frame BSAs share the same peripheral bits. the Triumph 500 single is actually the BSA B50 with different badges (pix in post 14).

    gonna be a good lookin' skooter
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  18. Nemosengineer

    Nemosengineer Hair Ball

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    Thanks for the parts connections if I have time tomorrow I will get on the phone, VFT is an old friend, that is where my alloy tank came from.

    Thanks again, Mike
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  19. Nemosengineer

    Nemosengineer Hair Ball

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    Hi Paul.
    I owe you a big "Thank You" as your post led me to SKF P/N 6302 QR C3, which is the 16x42x13 steel cage bearing you speak of. Its a "special" with the 16mm bore, it's a crank bearing for Motobecane moped engines. I have 4 each on order as of 20 minutes ago. This just made my life much easier.

    : Mike
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  20. Nemosengineer

    Nemosengineer Hair Ball

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    Hi Beezer,
    When Triumph moved the shifter they used a crossover shaft and ran it out the left hand side, the left hand shifters can be converted back to the proper side fairly easily using the earlier parts. Like any good puzzle figuring out what parts are compatible with the transmission you're swapping in is all part of the fun.

    : Mike
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