Fixing the 1980 yz465

Discussion in '2 smokers' started by mudmantra, Jun 19, 2012.

  1. anotherguy

    anotherguy unsympathetic

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    Yes,stock VM Mikuni.
    #21
  2. mudmantra

    mudmantra Been here awhile

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    Setting up a CR500 for the woods sounds cool. I never really thought too much about taking a big 2 stroke through the woods, but now I'm hooked. I have a TT500 4 stroke for woods riding and it's a blast too. But I've got the TT500 apart for some major work. So the YZ465 is now my woods bike, and it's been a lot more fun than I expected. :D I'll take some pictures of the YZ465 and post them here.
    #22
  3. anotherguy

    anotherguy unsympathetic

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    A tip. Check the timing and run it at the advanced edge of the range. Then jet to suit.


    A tired old image of my 465.

    [​IMG]

    They handle well with the tubes up in the trees too.

    [​IMG]
    #23
  4. mudmantra

    mudmantra Been here awhile

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    Nice YZ465:thumb. It's in better shape than my YZ right now. Mine has no decal on the tank too. I checked into a decal and the decal company said they might bubble or fall off plastic gas tanks. They said to empty the tank after every ride. I don't think I would do that. So I'm with out a decal right now. Good idea with the forks. I'll try that with mine too. A little quicker steering might be a good thing in the woods. Plus I like the idea of a lower seat height.
    #24
  5. mudmantra

    mudmantra Been here awhile

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    I got a few rides in. Hard to start but lots of power. :D Then I got some parts together to fix a few things. I pulled the exhaust off, so I could paint it. I then inspected the piston through the exhaust port. It looked real bad.:huh I pulled the cylinder off and it's going to need a new piston and cylinder needs to be bored over sized again. Already 1mm over stock. Who makes good pistons for these motors? A picture on a short ride. On the bright side, it well have even more power when I get it right. :D
    [​IMG]
    #25
  6. anotherguy

    anotherguy unsympathetic

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    Wiseco is your only hope other than a resleeve.
    #26
  7. brucifer

    brucifer Long timer

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    Your bike looks way better than my CR500, that's for sure. :lol3

    You have a PM. :D
    #27
  8. mudmantra

    mudmantra Been here awhile

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    I like the way the YZ465's look. I'm going to get some decals and freshen the looks up a little. The Honda CR500's are cool. I just talked to someone who had a CR500 with motor that's beyond repair. I don't know what he's going to do with it. I could check into it. Right now, I'm doing the math on the parts and work I need to do to get the YZ running good. I'm lucky that I just my dirt only XT500 running. At least I can get out in the woods, while I fix the YZ. :D
    #28
  9. mudmantra

    mudmantra Been here awhile

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    #29
  10. anotherguy

    anotherguy unsympathetic

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    I've had issues with Wossner pistons in a twin. The weight between the pair was 15 grams different. Just one instance but it did cure me of ever considering them again. Never seen that with Wiseco,ProX and OEM (ART).
    #30
  11. mudmantra

    mudmantra Been here awhile

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    Thanks for the advice. Wisco it is. I've used Wiseco pistons before in 4 strokes, and they worked well also. :thumb
    #31
  12. DocRogers

    DocRogers Been here awhile

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    My brother had one of these back in the day, the rest of us had IT 175s, YZ 125s, etc. we called the 465 the Beast, and it was a blast to ride. Here he is on it, circa 1981...[​IMG]
    Great bike! Enjoy
    #32
  13. mudmantra

    mudmantra Been here awhile

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    Yes I can understand the beast title. As soon as they're started that thought come to mind, even before the clutch is let out. :D
    I can wait to get it running again. As soon as the piston comes in, I'll send the cylinder and head to forward motion engines. Looks like the cylinder well clean out good at 86.5mm. While that's happening I found a lot of little things to fix. I'll just check it over one bolt at a time.
    #33
  14. anotherguy

    anotherguy unsympathetic

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    At 86.5 MM the liner is bound to be thin. A suggestion or two. First run 32:1 fuel/oil ratio. Second,run race fuel. Not necessarily high octane but a good leaded fuel. I like the VP U4 series. My YZ is only on the second oversize and when I rebuilt the crank it was only to balance but if it's in my hands it gets new bearings. There's much to be said for good fuel and I'm sure much will be said. :D
    #34
  15. mudmantra

    mudmantra Been here awhile

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    Sounds like good advice, because the fuel here is awful. I'm having the compression lowered slightly, for that reason. I'm sure it well still have more than enough power for the woods. All those trees coming at you, makes ya think your going fast anyway. :D
    #35
  16. mudmantra

    mudmantra Been here awhile

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    I have the YZ465 together again. I sent the cylinder and head to Eric Gorr to improve the power band for woods riding, and to run better on pump gas. Now it seems to be making a lot of power everywhere. :bmwrider I want to get the jetting right. With the 86.5mm bore, it's now at almost 482cc's. I looked at the Carburetor, and the jetting is. Main jet 390, Needle jet Type 166 Q-0, Needle 6DH4, Pilot #45. Slide is a 3.0. I want to try a 3.5 slide mod, but I think then I'll need to install a richer needle, Like a Q-8. Do the Type 247 and type 166 flow the same, if the size number is the same? And how did Yamaha use the type 247 needle jet in the mikuni carburetor? Dose it use a different spacer?
    #36
  17. athomerecords25

    athomerecords25 Banned

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    So many great threads like yours on the Yamaha YZ465's and mine has completely fell off. Thank you for keeping us all updated. I know I appreciate it and it gives me motivation.
    #37
  18. mudmantra

    mudmantra Been here awhile

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    Thanks. Just keep working on it. It's been taking me longer to get my YZ465 together completely, than I'd like. I wasted a month at least just trying to decide how to paint the engine. :1drinkNow the motors in and I started to think why did the last piston destroy itself. The bike runs great, but I want to have it last. That's why I'm asking more about jetting. This picture shows the motor in, I'll paint the frame later. I now have the pipe solidly mounted in. But I just bought new stock rubber mounts and well do it all over. :amazon
    [​IMG]
    #38
  19. mudmantra

    mudmantra Been here awhile

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    This is the carburetor on my yz465. The longer needle jet is a 247 and the shorter one is the 166 style. I bought a Q-8 247, thinking it would work and that I had a Yamaha mikuni. Well it had the 166 needle jet, so I guess it's just a standard VM38mm. Unless something is missing? Did Yamaha use a completely different mikuni carburetor body? Or did Yamaha use a spacer that allowed the use of the 247 needle jet? I looked up the yz465 carburetor, but some of the parts in question are no longer available. I ordered some more 166 series jets, just in case.
    [​IMG]
    #39
  20. mudmantra

    mudmantra Been here awhile

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    This is the old piston. This is what I'm trying to avoid. Plus I want the bike to start and run even better too.
    [​IMG]
    #40