Building a 1981 Yamaha YZ465 Factory Replica...

Discussion in '2 smokers' started by FJ_Kevin, Mar 11, 2012.

  1. wfopete

    wfopete Suffer Fools; Gladly!

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    Jeff Stanton, sorry typo.
  2. FJ_Kevin

    FJ_Kevin Been here awhile

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    ====

    Great photos and some wild machines you have there, thanks for posting this!

    Would love to here some more about your experiences with the 465/490. Did you rebuild all these bikes yourself? Any particular challenges or special tricks you would like to share?

    How do you like them? How has the reliability been?

    What did Broc have to say about your bikes, especially that 490... wondering how close did it felt to his old national bikes?

    Super post!
  3. FJ_Kevin

    FJ_Kevin Been here awhile

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  4. TennesseeVol51

    TennesseeVol51 Adventurer

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    Man I still enjoy this Thread!! Good Stuff!!
  5. FJ_Kevin

    FJ_Kevin Been here awhile

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    Thanks Tennessee! Always nice to hear that!

    Funny to see this thread pop up too as I have recently been look through the resto photos and at topics not yet posted, especially as I have got them fired up for the new season.

    One of these topics has to do with the importance of good quality lever assemblies. Now I cant say I am up to date on what's out there these days but one thing I do know is I like good quality non flexing clutch and brake lever assemblies. This is particularly important when running drum front brakes. It makes a huge difference in stopping power. That and good quality cables.

    During the assembly process, I was really surprised to see just how much flex there is in some of these cheap aftermarket lever perches.

    This is NFG if you want to go WFO and still be able to stop.

    So what am I using then? Magura baby!

    These German controls were hot setup in the 70's. Very firm and durable also. And the levers could really take a good amount of bending before breaking. They still sell them too.

    But I didn't need to buy new as I already had some from various Husky parts lots I've purchased. These were stock items on many of the Euro brands in fact. Husqvarna, Maico, KTM, the Spanish bikes too, they all ran Magura levers.

    There is one thing though I don't like about them. The cable adjusters. The diameter of the threaded section is just too small. I've had several instances where the adjuster has broken off in a simple fall leaving part of the threaded barrel stuck in the perch. And yes, I did not over tighten the perch, they were tight but could still rotate with some force. Still I was occasionally breaking the adjusters.

    As I am using old Husky Maguras, another issue was that the Yamaha cable casings are larger diameter than that used by Husky and so the cables would not fit in the euro sized adjusters. Now you can buy Magura adjusters to fit Japanese cables but that still leaves you with the small and susceptible treaded section. In fact, I put a brand new pair of Maguras on the #1 YZ465 complete with larger Magura adjusters. First time out I fell off and broke the adjuster on one.

    The solution for me this time around was to re-tap the perches on my used set to accept a common larger diameter Japanese style adjuster.

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    Tap is metric size M8 X 1.25 , I didn't find re-drilling to be necessary, I just threaded the tap right into the lever perch to cut the new larger threads.

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    Here is an example of the adjusters. The left two are Mugura adjusters, the left most one is actually bent a bit, it is one that will accept a Japanese cable. The one in the middle will only accept a euro cable (smaller diameter). The gold one is a common large diameter Japanese style adjuster. I've got several of these in a couple of lengths but show only a short one here.

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    If you do shop for some old Maguras you should know they come in a few different styles. There is the traditional perch and the split perch. Of course the split perch may removed from the bar without having to remove the grip.

    #2 YZ465 has a split Magura perch with the Magura adjuster as seen in the photo below. The lever is actually for the clutch side as the hole for the cable end would normally face down to keep the dirt from collecting.

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    Here is a better photo showing how the split perch comes apart. Also note that these perches are drilled to accept mirrors whereas the one above is not.

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    This next one may be an older version, it does not split so the grip must come off to remove it. The cast mark is there for the mirror hole but it is not drilled.

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    This one is similar but it is drilled for a mirror and has an additional hole for some kind of brake light switch I think.
    Note the smooth bore here.

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    Now compare that smooth bore above to this perch below with serrations.

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    Then there is the standard lever, the shorty lever and the black anodized version of the standard and shorty lever.

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    Is this dizzying or what?

    All this effort restoring these race bikes, you know, I want matching levels...is that too much to ask for?
    This is supposed to be fun. It's like trying to match socks for f'cks sake!

    Just saying... :-)

    More to come!

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    Baja Perro and juicy flawless like this.
  6. TennesseeVol51

    TennesseeVol51 Adventurer

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    I try to post a few pics of my 1985 YZ250 Resto when I get a chance.. Love the pic of the Montesa look at them head fins!!
    FJ_Kevin likes this.
  7. FJ_Kevin

    FJ_Kevin Been here awhile

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    Yes, post up some pics, Id like to see it. This has the red frame right? Cool looking racers!
  8. FJ_Kevin

    FJ_Kevin Been here awhile

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    I suppose it will not come as a surprise to most of you to find out that I have a fairly large collection of old motorcycle magazines out here in the moto barn. Yes, its true.
    The great thing about many of the old ones, and why I keep them, is the thoroughness and technical detail they often go into. It seemed like every bike test include a complete disassembly of the motor with in depth discussion of what was different from the previous model, why the dogs on the transmission gears sport a different angle this year, etc, etc. Always lots of hop up tips too and suspension upgrade how to's. I really ate that stuff up. And I don't know when it happened exactly but much of this kind of thing has faded away in most of today's rags, too bad.

    So all this round about chit chat was just to say that I have been re-reading some of this great stuff and happened to run across a very interesting article in the June 74 issue of Cycle Guide. It has to do with Gary Jone's National Championship 250 Honda Elsinore. Of particular interest to me and probably to some 465 folks is the porting on this bike.

    It is clear as day, right there on the 1st page of the article, that Don Jones implemented what most people today refer to as Boyesen ports!
    These are the ports that run from the intake port to the transfer ports. The Elsinore did not come this way, this is Don Jones' doing. Of course he is running a reed valve also, Yamaha YZ according to the article.

    In any case, the is the earliest use of the Boyesen port that I am aware of and am now thinking they should really be called Jones ports. It is an interesting article and has much more great stuff in its' nine pages, you definitely will want find that issue and give it a read!

    Oh that was mean wasn't it? Don't worry, I have ya covered right here! Look for Jones port shown in lower right photo, pg 61., enjoy!


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    More to come....

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    FR700 and brucifer like this.
  9. FJ_Kevin

    FJ_Kevin Been here awhile

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    So looking back I realized that my comments about today's motorcycle publications may have been a little harsh.

    There actually is one magazine that I have become fond of and that is VMX (Vintage Motocross and Dirt Bike Quarterly) magazine out of Australia.

    I even have issue number 1.



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    I find their coverage is very broad, lots of European and British bikes.

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    And plenty for the Yamaha fan also. Historical reporting and bike reviews are all very objective.

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    Highly recommended.
  10. brucifer

    brucifer Long timer

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    Hi Kevin. I happen to agree with your previous comments regarding how the old mags went into detail about the bikes. I have several Cycle Guide, Cycle World and random Dirt Bike and Motocross Action magazines from about 1979 to 1987 and the detail in which they got into the engine designs and so on was impressive. I always liked that aspect.

    I have a few questions for you. Having sold my later model dirt bikes, I currently own only one--my beloved 1984 TT600.
    The engine is new--bearings, rebuilt crank, cam chain, oil pump etc. Mods done include: 11.5:1 621cc JE piston, Web motocross grind camshaft and appropriate valve springs, ported cylinder head. This thing runs killer.
    The rear shock is a Works Performance unit and works great. The front forks need help. This is where you come in. :D
    I understand my forks are the same as your IT forks. Is there anything you have done to yours to make them a little more jump friendly? Do you know if there's any gold valves or cartridge emulators available? I do have a 2002 YZ250F front end I could install but I like the idea of staying with the stock set up--drum brakes and all. Thanks!

    Keep up the great work! I'm following all of your cool 2-stroke build threads.

    Bruce
  11. tHEtREV

    tHEtREV Encouragement award recipient. tEAM iDIOT.

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    I used to buy that mag, one of the few I would read cover to cover.

    Still have quite a few that I go back and look through. Only stopped buying it because of budget restrictions...
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  12. FJ_Kevin

    FJ_Kevin Been here awhile

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    Hi Bruce!

    Sounds like a real beast you have there. You need to post us a photo! I don't have much to contribute I am afraid. My IT490 springs are way too soft as well. The YZ's have either YZ springs or in one case springs from a 85 KX500. They are firmer than the IT for sure.
    All is not lost though, Michael N on pg 24 here is running racetech springs and emulators. I think WFO_Pete is also running race tech stuff. Maybe they can chime in with the latest thinking on all that.

    Hope this helps and thanks for the good word!

    Kevin
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  13. FJ_Kevin

    FJ_Kevin Been here awhile

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    Haha, yes, hate to think of the money I have spent on motorcycle magazines. Maybe that's why I don't throw them away!

    I do see the VMX mags "on sale" from time to time, especially around xmas. That's how I picked up some of the ones I have.

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  14. FJ_Kevin

    FJ_Kevin Been here awhile

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    It was a nice warm day in in Maryland. Spent most of the day cleaning up winter debris, fallen limbs and all the wild vine stuff that has grown all over the old horse fencing. Some of the fencing has fallen and Ive been working to pick up and remove that stuff too. I actually like the outside work and figure I need the exercise anyway. As for that fencing, some of it was in the way of my future addition to the farmadilla course number 1. Thinking about the new course additions was very motivating and I am excited about some of the plans for this.

    It wasn't all work though, I did get out the 490 for a little action today,

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    The bike is starting well. The last time I started it was on a particularly warm day in mid-February. Gas is from December, even so, three kicks and we had fire!

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    So she ran good and strong, very clean. Ive been back on the indoor trainer for the last 1.5 months (good thing too) so felt much better on it than I otherwise would have.

    One change I have made is the gearing. I was running a 14/49 but have gone up a tooth in the front to a 15. The 1st gear in the IT trans is lower than the yz465. This change made it much more usable.
    The bike has so much power though I am thinking about dropping the rear sprocket as well. I would like to set it up for a tall 2nd gear or maybe 3rd gear start. Still some experimenting to do.

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    No personal photographer today so stills will have to do.

    I'll sign off with this last shot of this Maryland farm fresh tilled loamy soil courtesy of the mighty YZ490!

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    More to come...


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  15. tHEtREV

    tHEtREV Encouragement award recipient. tEAM iDIOT.

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    I have a big pile under some book shelves from 81 to current (mainly from the 90s though), and my wife suggested I throw them out, I said I can't, and in fact I need to collect more, because all the bikes I buy are old, so I need them for research.:D

    It is nice to be able to flick through an old mag and get reviews and info on how they used to set them up when I get a new (old) bike.
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  16. brucifer

    brucifer Long timer

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    Hi Kevin. Here's a couple pics of the TT600.

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    I have new Yamaha fenders, aftermarket side covers (from Germany!) and tank graphics ready for installation. The front fender is actually for an XT600 as I couldn't find the correct TT one. It's pretty much the same but without the rear louvers.
  17. FJ_Kevin

    FJ_Kevin Been here awhile

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    Wow, that bike looks to be in excellent shape. I can understand why you like it. Can't help but notice that many parts look like those on my IT490, swing arm, forks and wheels are the most obvious.

    Very cool bike, thanks for posting!
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  18. brucifer

    brucifer Long timer

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    Maybe you've seen this one before but if not, here's a neat old video of our bikes battling it out--well, maybe not so much battling it out as your bike staying in front. lol. The important thing is, it's Yamahas 1 and 2. :-)

    Baja Perro and FJ_Kevin like this.
  19. Greco

    Greco Braap!

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    Any one know where I could find an air filter cage for my 1984 YZ490? The guy I bought it from gave me the air box, but no cage to hold the filter. He was running a pod filter like you would see on a pit bike. Our vintage season starts out here next weekend and I'm nervous about that filter.
  20. Scootern29

    Scootern29 Long timer

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    See if Uni Filter sells their filter with a cage.