The Compleat Yamaha TY80 Thread!!

Discussion in 'Trials' started by Brewtus, Apr 28, 2010.

  1. lineaway

    lineaway Long timer

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    Hate to tell you, but that is a GT80. Not a Ty 80.
  2. Brewtus

    Brewtus Buffoonery, Inc.

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    GT tank, seat, bars and pipe anyway. Maybe a "bitsa", but can't really tell.
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  3. UstaKood

    UstaKood Been here awhile

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    Yep . Frame /motor should have #451 prefix .
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  4. upperleft

    upperleft Been here awhile

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    Yeah I guess it must be a gt80 or mx80? The vin is 367-1007xx. Anyone know what that means? Sounds like all these models share the same engine parts. What are the differences? Just the frame?

    This engine needs a complete rebuild and has a crack on one of the engine cases. I think I have everything I need on order. Just need to find a local shop to bore out my cylinder. Does anyone know what CCs a +1.50mm (48.5mm) bore would be?

    Is there anything I should do or look at while doing the rebuild? Plan to clean and inspect everything and maybe some paint on the cases. I will work on getting it running like it should then move on to the suspension making it look half decent.
  5. Brewtus

    Brewtus Buffoonery, Inc.

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    367 prefix is a GT80. :thumb
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  6. upperleft

    upperleft Been here awhile

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    Thanks. Do you know of the gt and ty engine cases are the same?
  7. Brewtus

    Brewtus Buffoonery, Inc.

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    Dunno. Probably. Never had a GT80. We've had a couple of TYs that had GT80 top-ends on them, so they probably are. As far as primary and gear ratios go..... :dunno
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  8. UstaKood

    UstaKood Been here awhile

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    Far as I know ( which admittedly is well .. ) Most parts are interchangeable .

    Trans ratio's different and I suspect different cylinders ( a good gt ,"gitz' pretty good )!

    Frame / triple clamps are different .

    But , if nothing else you'll have a good pit bike ! :thumbup
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  9. upperleft

    upperleft Been here awhile

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    Thanks for the info. I also found a mx80 in my area I might pick up of they come down on the price a little. Really I would like to eventually have 2 of these bikes. One for me and one for the fiance. It is always helpful to have 2 bikes that share spare parts.

    It would be great if anyone could list out all of the differences between the ty, dt, and mx.

    I am a little disappointed this isn't the ty but I think it will still make a fun play bike.

    Pm me if any of you are trying to get rid of extra parts. I could probably be talked into buying a bunch of stuff I don't need.

    Thanks again for all the info.
  10. Brewtus

    Brewtus Buffoonery, Inc.

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    'Nudder top end ready to go. Piston and cylinder will be sent to Albuquerque Monday morning for bore work. Fabbed up a crank seal driver out of PVC since I had the lathe all fired up.... :D

    20200530_134922.jpg
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  11. Ymirtrials

    Ymirtrials Long timer Supporter

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    I often worry when I see a carbide in the die grinder next to what likely was a good cylinder....:hmmmmm






    :D
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  12. Brewtus

    Brewtus Buffoonery, Inc.

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    Just knocking down some casting "gravel", that's all. Nothing too outrageous going on here, nothing to see, move along now..... :brow
  13. Brewtus

    Brewtus Buffoonery, Inc.

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    Picking up the above top end on Friday at the MWVTA event in Colorado. In the meantime, another crankshaft/crank bearing replacement. The top end of this one was done just a couple of years ago, and the newfound compression made the old crank bearings very unhappy so......

    20200614_151723.jpg
    :D
  14. Brewtus

    Brewtus Buffoonery, Inc.

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    One done, one to go.

    Top end assembled on the first one, fired it up in the chassis shown above, new crank and top end happy!! Discovered a wrist pin bearing falling apart in the second one, and the wrist pin was pretty unhappy. :confused Piston still fit in the bore nice but....

    New piston ordered to go on the fresh crankshaft/rod assembly. Hone the cylinder, and chuck it up in the lathe to take a nice shallow "skim" off the gasket surface that always makes the beer can gaskets smile -

    20200718_173954.jpg

    Everything going along just fine when ALL OF A SUDDEN the cut didn't sound so happy. The cutting edge of the tool decided to chip just then, making the rest of the pass look like an old Iron Butterfly album. Damn. Dressed the tool as well as I could, and a "skim" pass across the failure point made it.....better. Do I have another facing tool for the lathe? Hell no, why would I? Since I have several other bikes begging bench time, I went with an old standby. 220 grit sandpaper on a plane of glass, some Bel Ray 6 in 1, and time.

    20200720_134413.jpg

    Went ahead and planed the head too. Why not? There's no real rush, but I did want to get this one assembled and running by tomorrow (or thereabouts). After all if this bike doesn't run by tomorrow, we LOSE THE SHOP!! :rofl

    Both surfaces happy, and head gasket material ready for fab. :D

    20200720_140837.jpg

    Gotta get 'em ready to sit around this year after all. :thumb
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  15. motobene

    motobene Motoing for 49 years Supporter

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    Nice work, Brewtus! Interesting your orientation the red carbide cutting tool in the tool post. It's faced in instead of the usual up. How the heck does it cut that way? Or is it a test to see who is paying attention?:y0!

    Beer can gasket. Interesting! I've used nothing but a mere skin of Silicone 1 if the squish isn't too narrow without a gasket.
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  16. Brewtus

    Brewtus Buffoonery, Inc.

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    Sharp eye. It was to see if I was paying attention when I threw it in the tool holder. Took the pic, went to start work, and "what the...." :eek7 What the heck, I wanted a set of indexable carbides anyway. :D
  17. motobene

    motobene Motoing for 49 years Supporter

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    I just thought maybe I was missing some machining trick like skimming cross ways with the cross slide :-)
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  18. Brewtus

    Brewtus Buffoonery, Inc.

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    Nope. The tool had been used the "other way" in the past, I think I just slapped it together wrong looking at the hold-down prints. In all honesty that tool wasn't in the best of shape to begin with, and my "dressing" of the bit didn't help one damn bit (I don't have a green wheel). Hey, it came with the lathe, and it was the only 1/2" tool I had to work with. Yeah, I fucked up. I'm man enough to admit it, who cares? :dunno

    :D
  19. jonnyc21

    jonnyc21 Trials Ninja

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    What’s life without a bit of self inflicted pain once in a while? :1drink
  20. Brewtus

    Brewtus Buffoonery, Inc.

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    If it ain't smokin'..... :evil

    20200723_125721.jpg

    'Nudder teammates spare bike done. :thumb
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