Project 1976 Yamaha YZ400

Discussion in '2 smokers' started by craydds, Feb 22, 2013.

  1. craydds

    craydds Long timer

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    I just bought a '76 YZ400! I know, it's a sickness. It seems to be all original and unmolested, except for the gas tank. (pics to come later). Seems rare to find an old dirt bike (or any old motorcycle) that has not been tampered with, or TRASHED. The gas tank has been painted flat black - possibly to hide some bondo repaired dents? We shall see. The rear shock has NO damping, none, it is gone. I'll do a shock rebuild search, see if anyone does rebuilds, or possibly can tell me how it's done. Yeehaw, another project!

    edit: Is there a YZ400 thread? I did not do a search.
    #1
  2. craydds

    craydds Long timer

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    Let's start a Yamaha YZ thread to include ALL the YZ's. I now have two, a 1980 YZ50 and my brand new old '76 YZ400. Remember, they were the FIRST with the MONOSHOCK. That was so cool! Elsinores were nice, Suzooks were good (I had a 125 and a 250), but the YZ's had that monoshock.
    #2
  3. heliyardsale

    heliyardsale Always looking for Dirt!

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    Ha! I bought the same bike last week! Here is mine stuffed in my car! I also have a 76' YZ100C and the YZ125X.
    [​IMG]
    [​IMG]
    Bad photo of the clan!
    [​IMG]
    #3
  4. heliyardsale

    heliyardsale Always looking for Dirt!

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    Here is my YZ125X
    [​IMG]
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  5. craydds

    craydds Long timer

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    Wow! That 125 is NICE. I like that gas tank for the 400 shown in the post above. I saw one on ebay but I was unsure about it. I got a Clymer's manual with my YZ400, it SUCKS - conflicting info, etc; I bought an "official" YZ400 service manual from ebay - a gamble, but shall see if it is any better. I see that Racetech can rebuild shocks, may give them a call: http://www.racetech.com/page/id/64 . Got the bike home yesterday and it FIRED on the second kick. Started doing some cleaning up, going to lube everything, etc. I need a rear fender... ebay again? The project begins. (I will get some pics today.)
    #5
  6. craydds

    craydds Long timer

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  7. craydds

    craydds Long timer

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    [​IMG]
    Will get some things cleaned up, lubed, and adjusted today. Take it for an easy test ride in the desert. A 400 cc 2-stroke! Bet it will have AWESOME power.
    #7
  8. heliyardsale

    heliyardsale Always looking for Dirt!

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    Lolls pretty good! Don't lose the silencer, they cost huge $$$ to replace.
    #8
  9. craydds

    craydds Long timer

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    Rear wheel off. Axle, dirty but in good condition otherwise:
    [​IMG]

    Rear wheel is good:
    [​IMG]

    Everything covered in many years of dirt. Rear monoshock bolt ready to come out:
    [​IMG]

    Swingarm loose. Look at that "inner fender", it's a piece of rubber floor mat:
    [​IMG]

    Another view of the rear "inner fender". Anyone have a source for the correct part? ebay? :
    [​IMG]

    The front monoshock bolt needs to be removed:
    [​IMG]

    That nut is too TIGHT. I cannot get it to budge. Any tips on how to loosen it?
    [​IMG]
    #9
  10. crg infidel

    crg infidel Adventurer

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    First and foremost, Sweet Bike!!! That is gonna be a ton of fun!

    It might be helpful to get some heat on that nut, but not so much you burn up your rubber. You could try a wet rag around the rubber bits, and a little propane torch to warm up that nut. (please be ready to put out fires; I'd hate to hear a horror story :eek1 )

    I grew up with old ring-ding Yamahas, and they are great bang for the buck!

    Good luck!
    #10
  11. craydds

    craydds Long timer

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    I will try and work it loose this evening. Get out my torch... and fire extinguisher. Ha!
    #11
  12. dooder

    dooder Adventurer

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    I can't tell from the pic... It's not reverse threads is it?
    Cool bike!
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  13. craydds

    craydds Long timer

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    I thought about that. I looked closely, but I'm blind in one eye... can't see out of the other. I could try to thread a nut onto the exposed threads to verify right vs. left hand threads. I will double-check that this evening.
    edit: I zoomed in close on the photo in iPhoto, threads look like right-hand. It is hard to tell, will check tonight.
    #13
  14. adventuro

    adventuro Adventurer

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    If nothing else works you could try a nut splitter, better than screwing up threads on the shock...btw I still have my 78 yz400 that I bought new.
    #14
  15. craydds

    craydds Long timer

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    I was ready to buy a nut splitter! But, I used penetrating oil and my torch - slightly scorched the rubber - and got the shock OFF:
    [​IMG]

    It was really HARD to get that nut to bust loose and I did mess up the threads a bit. Nothing that a die can't fix:
    [​IMG]

    Will clean up the shock and send it off to Racetech - http://www.racetech.com/page/id/64.

    Next step - I want to take the swingarm off. Same thing again - the swingarm bolt will NOT come out:
    [​IMG]
    #15
  16. stainlesscycle

    stainlesscycle Long timer

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    ooh boy, are the old swingam bolts fun or what?

    there is no good way. lotsa heat, frame securely mounted on it's side and go at it. or fit it into a press if you can. or try a impact hammer. anyway you go at it is not pretty usually..

    i have a very stubborn 94 yz250 linkage bolt that dpo ran with no nut on it or grease for apparently forever. it's really in there - gonna weld a stud to the head of it and make a puller i think..






    .
    #16
  17. craydds

    craydds Long timer

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    Impact hammer crossed my mind, might rent one or an electric jack hammer (kinda the same thing). I like to take things apart, clean, and grease 'em. Might have to leave this one alone; it seems to articulate reasonably well. I pumped some grease in it so maybe I ought to button it up and ride it.
    #17
  18. craydds

    craydds Long timer

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    I have a Kawasaki KLX300 and a Honda XR200 that are in great shape, and they are good bikes for the desert, so I am not without wheels. But, I have been wanting a big-bore 2-smoker; I saw this one on CL so I bought it. I did mention that this is a project bike?
    Sorry, out of focus, I was shaking. That huge motor scared me:
    [​IMG]
    #18
  19. Scootern29

    Scootern29 Been here awhile

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    Hey Ray, There is an air box on ebay for that bike. I saw it today while searching "1976 YZ400". Seems like it was $25.
    #19
  20. craydds

    craydds Long timer

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    Cool, thanks for the info. I will check into it.
    #20