Building a 1981 Yamaha YZ465 Factory Replica...

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

  1. anotherguy

    anotherguy unsympathetic

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    Shiny and pretty. But it's a garage Queen. Not what they're made for. I still ride and even race my YZ465 occasionally. And do pretty well too. It might be old but it was the cream of the class. Others made more power,some turned better but none had the package balance.
    #21
  2. Donkey Hotey

    Donkey Hotey De Jo Momma

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    Maybe so but, that ain't no YZ. Dead giveaways are the aluminum tank, the straight bars on the swingarm, the lettering on the right side engine case, etc. That's a real OW. :tb
    #22
  3. anotherguy

    anotherguy unsympathetic

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    yes it is. And they were made to ride as well.
    #23
  4. Afry

    Afry Why hike?

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    Great thread! Sure brings back some great memory's.

    I used to ride 490's on short hard pan tracks in Nocal - Baylands, Santa Clara PAL etc and found out that the bike flat hooked up by lowering the compression. I stacked two copper head gaskets on top and let her rip.
    #24
  5. FJ_Kevin

    FJ_Kevin Been here awhile

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    Sniper X: Nice photos... yes that is Rick Burgetts OW41

    Those photos reminded me to pass along these two books that I have been really enjoying. You will find plenty of good information on the OW Yamahas in these. Both include lots of great photographs and comments, even some from the riders who rode these machines. I found it very interesting to compare various aspects of our production bikes with what was done on the factory rides.

    [​IMG]

    VMX magazine is another great resource. They have run several features on the Yamaha factory racers as well as articles covering restoration of the production bikes. Many of the back issues are still available.

    Then there are the period magazine reviews. I found some of these in the Yahoo YZ490 group and others in the IT Enduro Club ( http://www.yamahait.com.au/forum/ ) . Even more YZ tests can be found here ( http://www.simnet.is/skulitho/YZ_stuff/ )



    Now, turning back (yuk yuk :evil ) to the rear wheel discussion...

    I wanted to point out a difference between the OEM Yamaha spokes and the Buchanan stainless spokes. The OEM spokes are butted (thicker diameter) at the end. The Buchanan stainless spokes are straight guage.

    I am wondering if someone can comment on the general durability of the stainless spokes. Are they more or less reliable than the OEM's. They certainly look great, how do they hold up?

    These photos should show the difference in spokes and the differences in the brake plate/spacer setup.

    Here is the yz490 with butted spokes at the bend. There is no space between the plate and the swing arm, only the dust cover for the brake plate bushing.

    [​IMG]


    Now, here is the '81 yz465 wheel with Buchanan stainless spokes. You can see there is no change in diameter at the bends. On the '81, the spacer is welded to the chain adjuster (I've rotated the brake plate to get a better view).

    BTW, the 490 has the nice aluminum brake arm. Much nicer than this ugly stamped steel thing I found on my 465.

    [​IMG]


    Finally, here are a couple of tools that have come in handy through the years.
    On the left is a cheap tire bead breaker. I guess I wouldn't want to bring it on the ISDT but does make tire changing around the garage much easier. I can do motorcycle and car tires with this and a big set of spoons I have.

    On the right is a wheel truing stand my father made in around 1970. As a kid, I remember him cutting threads for it on the lathe. Then he had me hold a piece or 2 in place while he laid down some tack welds.

    And before anyone asks, this is not my wifes living room....oh, no,no,no.
    This is the finished upstairs of my moto barn.:1drink
    [​IMG]

    So how about it "anotherguy" you like those "fancy dan" stainless spokes? Breaking any?

    And for Riceless950...

    #23 Marty Moates on his 1980 LOP YZ465 showing em how its done!


    [​IMG]
    #25
  6. FJ_Kevin

    FJ_Kevin Been here awhile

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    OK... with the 490 rear wheel worked out I was able to install the swing arm for the final time.

    The next step for me is to work out a 43mm fork swap. I also picked up a used, side port, DG YZ- 490 pipe that I will adapt to the 465. The original pipe was patched and welded numerous times so I was happy to get this pipe at a good price. Comparing the pipes, I found the 490 one to be very similar to the 465, the main difference being in the length of the stinger and how it attaches to the silencer.

    This photo below shows the bike with modified swing arm,YZ490 wheel, and a set of 1983 43mm IT-490 forks (more about that later). A motor was fitted temporarily to help work out the mounts for the DG pipe and new silencer.

    You may also notice that I have mounted the aluminum rear brake stay from a yz490 in place of the steel 465 arm.
    It appears the 490 arm is a bit too long as the plate is rotated in clockwise direction too far. This compromises the positioning of the brake actuating arm. My plan is to cut and reweld the stay arm at the rear attachment point. It will also be necessary to fit a spacer at the frame side as the arm eyelet not as wide as the frame bracket it bolts into.

    [​IMG]

    Chain Guides:

    Old plastic chain guides can get brittle and break thereby jamming the drive train. To avoid these issues, I went ahead and replaced all the guides and chain rollers. Fortunately, all the chain guide plastic is still available from Yamaha as well as other sources.

    The rear guide itself is made from aluminum and quite light. In addition to plastic, mine required cleaning and some new screws. The inside of the guide bracket is left bare aluminum. The outside part is repainted using a "hammered" finish that is durable and effective in hiding minor imperfections.


    [​IMG]

    Next up will be fork swap details. But first,

    [​IMG]
    #26
  7. anotherguy

    anotherguy unsympathetic

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    Nope. Not yet. But they're just 11 years old. :D
    #27
  8. lemieuxmc

    lemieuxmc Banned

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    The brake stay arm is supposed to form a parrallelogram with the swingarm so bumps don't affect the braking action.

    I attended the premiere of the USGP movie in San Diego and bought a Marty poster... what a great night!

    [​IMG]
    #28
  9. anotherguy

    anotherguy unsympathetic

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    I went out to the garage and measured the spokes while Dog was eating. The front spoke is .143" and rear measures .157". Butting spokes is a strengthening practice for weight savings. Doesn't make that spindly thing as strong as a straight gage spoke except in the loaded area by the hub.

    A double butted spoke (both ends thicker) has more elasticity than a straight gage and will tranfer loads to adjacent spokes under heavy loads to avoid breaking. But that's more for bicycle wheels where they're treading thin ice on strength. Like I said those spokes have some mileage on them and............well I'm no lightweight so they've been subjected to considerable punishment.

    My CRF 450R has straight gage stainless spokes as well and they are 8 years old and subjected to the same punishment. When you carry my bulk saving weight by the gram is simply nonsense. :D
    #29
  10. FJ_Kevin

    FJ_Kevin Been here awhile

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    lemieuxmc - Thanks for the reminder about this. I measured the 490 brake stay to be about 3/4" longer than the 465. Doesn't sound like much but it causes some interference back there. I am going to try and shorten it tomorrow.

    I would have loved to attend that event. I did pick up the DVD this winter and really enjoyed it. Also the extra clips of the Moates bike being prepped at Vintage Iron. The race itself was great!

    [​IMG]
    #30
  11. FJ_Kevin

    FJ_Kevin Been here awhile

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    Thanks for the measurements and feedback. Those Buchanan guys have been around a long time. I remember them in the '70's. There was a nice article about them in Motorcycle Classics, it was great to see they are still around.

    I agree with you. I am sure those spokes can take much more of a beating than I can these days...

    [​IMG]
    #31
  12. FJ_Kevin

    FJ_Kevin Been here awhile

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    43MM Fork Upgrade

    Alright, I will warn you now I may have gone a bit overboard here :puke1 but maybe someone else will find this info useful :deal

    As others have mentioned, the 1980 YZ465 used a 38mm fork with double leading shoe front brake (the 1980 YZ250 used a single leading shoe brake - correction per Greg below, thanks!). For 1981, Yamaha upgraded the 465 with a 43mm fork and continued with double leading shoe front brake. The 43mm fork and DLS was also used on the YZ/IT490's and 250's until 1984. In 1985, the DLS brake was replaced by disc.

    There are a few things to be aware of when considering the 43mm fork upgrade. First, ahrma post vintage rules require drum brakes. So for me that meant a pre-1985 fork. Second, there are two styles for DLS brake plates. The difference is in the location of the anchor tab. The 1981 brake plate has the anchor in the 1 o'clock position which the '82-'84 plates have it in the 3: o'clock position.

    This means the '82-'84 brake plate will not fit the '81 43mm fork slider and vice versa.

    If you wish to stay with a 38mm fork on your 1980 YZ250, you can upgrade to the DLB but it must be the 1980-81 YZ plate.

    The following pictures compare the front and bake of single and double -leading shoe brake plates.
    Left is the single leading shoe, anchor at 1 o'clock. Right is 82-84 DLS plate with 3 o'clock anchor.

    [​IMG]


    The next photo shows the 1981 DLS brake with 1 o'clock anchor. You can also see the corresponding difference in the brake tab location on these two 43mm fork sliders ('81 yz465 slider on left, 83 IT490 slider on right).

    [​IMG]

    A couple of more things,
    - The brake levers on the '81 DLS plate are steel, the later levers are aluminum
    - The DLS brake shoes are different than the SLS shoes.
    - The brake springs are the same.
    - Be sure to clean and lube all the pivot points, it makes a big difference!
    - Adjusting the DLS takes some patience to get both shoes to hit the drum at the same time.

    Now, while it is true that the fork tube diameter was the same across many years of the 490, the fork internals can vary significantly from one model year to another.

    Examination of part numbers show differences in springs and damper rods through the years as well as the appeance of a new device called a compression damping blow off valve.

    The compression blow off valve was introduced on the ’83 YZ/IT 490. As I had a set of '83 IT forks around, I did some searching for more information about this feature. According to Cycle Guide “The 43mm 1983 YZ/IT490 has a compression damping blow off valve that momentarily unseats and allows the fork to compress more easily when the wheel hits a big or abrupt bump. It is non-adjustable, unlike on the KX500 of the same year. The YZ wheel travel is 11.8 inches”.

    As I also have a set of disc brake forks of unknow year, so I did some reading on thoses as well.

    It turns out, the 1986 forks have 8-position compression damping adjustment. An alumite slider coating was used by this time “to reduce friction and oil contamination”. Fork action was give a favorable review in April ’86 issue of Dirt Rider. Another change came in ’87 with a new “travel control valve” or TVC. Unfortunately, TVC was given a poor review with Dirt Bike (1987) complaining of the “extremely harsh set of front silverware”.


    What fork parts are shared across model years?

    In the end, I wanted to use the best possible parts from the different fork sets I had. I compared part numbers for the various internal components and create this table to help spot which components were common between the model years.

    In the table below, the model and year is labeled accross the top row and the part is labeled in the 1st column.


    The letter A is used to denote the 1st version of the part for a particular row. The '81 model is the 1st fork considered so all the parts are of version A. If one looks at fork seals across all model years you can see they are all type "A" so this means they have the same part number and are interchangeable. The slide bushings and slide pistons are also shared across years.

    If a part changes, say from A to B, across model years it means the part number is different and they may not be intechangeable.

    Looking at the damper rod you can see they differ for every model year for the YZ. However the rod is the same for the 83 and 84 IT.

    [​IMG]


    More to come I'm afraid:eek1

    [​IMG]
    #32
  13. Donkey Hotey

    Donkey Hotey De Jo Momma

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    Nope, 1980 had the DLS brake as well. My bike was 100% bone stock in 1982 and it had one.

    Edit:
    This picture ran with the magazine test in--I think it was Cycle--in 1980 (duh, says so on his jersey). You can plainly see the brake.

    [​IMG]

    Edit 2:
    Hell, I forgot I had this posted out on the web. That's me with my bike in '82 or '83--Gold Belt, Hi-Points, Griffin pants--and a full head of hair. :lol3

    Pretty sure that was a first generation Terraflex on the back and a Vesco desert tank.
    [​IMG]
    #33
  14. dtysdalx2

    dtysdalx2 PITA but useful

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    Wow, great pictures!! :freaky

    The reason I like the old dirt bikes is all the rich kids had them when I was growing up and all I had was a DT125. I always sat in the library and read Dirt Bike magazines growing up. About 30 years ago.. :huh
    #34
  15. FJ_Kevin

    FJ_Kevin Been here awhile

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    #35
  16. Sniper X

    Sniper X De Oppresso Liber

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    That isn't a garage queen, it is a genuine OW factory machine. It probably has more hours on a track then any twenty YZ465s do all together! :clap
    #36
  17. Foot dragger

    Foot dragger singletracker

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    I was at Hangtown back when it was up by Placerville,It was early/mid 70's and Hannah was easily the most spectacular to watch,and fun to meet in the pits,friendly and easy to talk to. Danny Chandler showed up on a KTM 125 and was flat amazing,not a fast bike but holy jeeze could he fly that thing around with the throttle stuck open at all times!
    I saw Danny Laporte snap the ft end off his works Suzuki.

    We camped out with thousands of other lunatics in some farmers big field,huge bonfires,mini bike races all night,station wagon races,drunken bufoonery,what a blast!

    Nice build on the 465!
    #37
  18. supervision

    supervision Been here awhile

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    Hangtown , ealyl 70's was the high point of my racing. I finished high enough on Sat. 125 sportsman, so they let you ride, 125 Pro race Sun. I was so stoked, I hole shotted the first moto, even led for part way round!! WhenI came around the first lap people on the fence in the first turn, were cheering me on. Oh ya I rode Penton green fiberglass model,
    #38
  19. ctune80

    ctune80 Been here awhile

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    This is a topic that hits pretty close to home for me. I wanted one ever since
    Marty Moates won the USGP in 1980 on the LOP YZ465.

    Here is a photo montage of my 465 from back in '81. We had just got back from
    the Western Pacific, and I put it together on the Flight Deck of USS Mt Vernon
    by the light of a battle lantern.
    The next morning when I got off duty, I rolled it up to the Quarterdeck and requested
    permission to go ashore!

    One of the bottom pics is it sitting on the pier.

    Still ride it from time to time, way fun bike. Lots of power.

    [​IMG]


    Here's an action photo of the bike taken near Carlsbad Ca, in 1981. Wonder if I still have that gear....

    [​IMG]

    I will keep watching the thread for progress on yours!
    #39
    ozadvntr likes this.
  20. dtysdalx2

    dtysdalx2 PITA but useful

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    You still have it? Original owner?? :huh

    Sweet!
    #40