Building a 1981 Yamaha YZ465 Factory Replica...

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

  1. Scootern29

    Scootern29 Long timer

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    Those fender braces are cool. I have 3 or 4 of them stashed away in one of my sheds. Acerbis made a really nice one also.
  2. FJ_Kevin

    FJ_Kevin Been here awhile

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    Yeah, they are cool. I have an extra for the IT490 but have not mounted it yet. BTW, I ran across this photo and was wondering if this was one of your Husky/CZ specials?

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  3. FJ_Kevin

    FJ_Kevin Been here awhile

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    OK boys, wish me luck!

    It is Friday night and the truck is loaded up for another shot at the Johnny B cross country race tomorrow here in Maryland. This will be my 4th attempt at this event. I need the luck too as I have yet to finish one :muutt.

    I quit the 1st one due to exhaustion (oh the shame). The second attempt ended in the bottom of a creek after being blown off by some youngster. Last year... well I just realized I never finished the report on that one... let's just say it wasn't pretty! I'll come clean on that one later :-).

    I've made some attempt to tune up for the event but there is no question my friends, age is catching up I think. In any case, the bike is running terrific, really strong and so I will give it my best too.

    To that end, :sweeti snapped a number of photos over the last couple of weekends to help in assessing position on the bike and suspension settings. I've put on some lbs I am afraid and didn't realize how much the suspension was compressing, even in the turns. I guess i'll have to work on that, trouble is we have this really good bakery near the farm :deal.

    First is this photo of my training partner Lucy. She is 12 years old and still goes pretty good. Lucy gets worked up as soon as put my gear on. Go Lucy go!

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    So one thing I have been working on is sliding further forward in the saddle for the turns. The IT has a big tank so this takes a conscious effort.
    And it has been helping as I feel like I can push the corners harder without loosing the front wheel. I'll be thinking about this a lot tomorrow as this is where things went wrong last year in the mud.

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    There are quit a few flat grassy corners on the farm that can also be pretty tricky, especially when damp. That left leg has no ACL and is a little delicate. This photo reminded me to be a little careful and to watch how far I stick it out there in the left handers.

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    This next photo surprised me in terms of how far the suspension compressed in the turn. The frame and kickstand are dragging in the dirt. The front really dives under braking. What a fatty!

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    Of course it not all about the turns. It is a real balancing act when these big bores hook up. Too much wheel spin when far forward.
    Too far back and you have to shut off. Right hander coming up...

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    BTW, couldn't help noticing the resemblance in form to this photo of Jim Pomeroy! :rilla

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    This one is kind of interesting too. This turn is on the top of an uphill. There is no berm but the farm grass really holds you here.
    It was a surprise to see the right peg in the dirt of a flat turn like this. Who says Yamaha's don't turn?

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    This one was kind of fun. I remember ducking my head to avoid the branches.

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    So there you have it. I think the main goal for tomorrow will be to have fun and just finish.

    Above all else I want to avoid falling off and injuring myself... :sweeti has already told me there will be no day off on the farm!

    More to come!

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  4. Scootern29

    Scootern29 Long timer

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    Not one of mine. I think that pic was taken at the original CZWC at Saddleback. MXA did a couple of CZ Husky bikes. Could be one of them.
  5. Chappy58

    Chappy58 Been here awhile

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    Will be watching this thread. I'm just starting my '83 YZ 490 restoration. So far it the bike has been brutally disappointing. The frame was bent and repaired, I was able to find another out west. It'll be here next week. Split the cases on my IT 490 parts bike last night. The YZ will come apart today. Whatever arises out of both will be good as new. Good luck at the event today!

    Chap
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  6. wfopete

    wfopete Suffer Fools; Gladly!

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    Kevin, look at the bright side: With your suspension compressed your CG is lower and your wheelbase is shortened, making that IT a turning fool. But please, keep your feet up and off the ground. A grassey field in one thing but a rutted course is another. Dragging your feet is a bad habit that can get you really hurt. Good luck and let's hear the outcome of this ride soon!
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  7. FJ_Kevin

    FJ_Kevin Been here awhile

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    What a great time at the Johnny B!


    It didn't quite turn out as I had hoped in terms of finishing but sure did in terms of having fun.


    Now, before all the photos etc, I am just going to come out with it as far as my result. The bottom line is I failed to finish once again, rats!... but I came close to finishing and with a good position too, that is, before a mishap took me out. More about that later.


    Anyway, we had a very nice day for the event. Sunny and cool in the morning with a little overcast and breeze in the afternoon. The leaves are changing here in Maryland, so very picturesque. Recall this event takes place on a beautiful 40 acre farm with a course composed of twisting trails through the woods with a spattering of more open sections (although perhaps not open enough for that big 490!).


    And the big 490 was running good too. I'm finding that all these big bore Yamahas have kind of a bad-ass reputation and that reputation seems to be growing. It was probably the fastest thing there that day although certainly not the fastest in the tight stuff. You can feel the weight of the big brute through the wooded switchbacks. The bikes drew a crowd and plenty of fun comments.


    So the good news is the chick was there with her camera and she snapped quite a few photos throughout the day. I snapped some too.


    Here we have the bikes just after arrival and ready to go. I brought the YZ465 along for spares and maybe a little extra intimidation. Certainly the bikes looks more intimidating than the grey haired geezer who rides them. Have a look,

    [​IMG] [​IMG]


    Word seems to be getting out about the Johnny B as turn out was great. Lots of vintage and post vintage bikes. This year they they had enough riders to run vintage class separately and then followed by the post vintage classes an hour or so later. Each race was an hour long. If you had bikes for both classes you could race two whole hours! There was a class for the modern bikes too although that was not the primary focus of the event. They ran with the post vintage group but started 40 sec ahead of the first PV wave.


    Before getting to the racing, let's have a walk about the pits and check out the bikes.

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    The guys above came out of PA and were good friends and old racing buddies from back in the day. The fellow in the black jacket has a '79 Maico Magnum but wasn't racing this day. Had fun talking with them all.

    Next up are these amazing Bultaco's. They were real beauties!

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    Then there was this free roaming guy,

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    Haha, I did say it was a farm!

    Still uploading the photos so more Johnny B to come...
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  8. FJ_Kevin

    FJ_Kevin Been here awhile

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    So continuing on a bit,

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    I kind of liked this KTM... didn't see the owner around so unfortunately no back story on it. A 175 perhaps?

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    Here is that neato Bultaco again. And look, one of those rare yellow frame Yamahas.

    [​IMG] [​IMG]


    More to come...
  9. Grinder74

    Grinder74 Adventurer

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    I just read this whole thread over the past couple days and it has been a great read. I'm very interested in your 1983 YZ490 build as that was my first dirt bike and 2nd motorcycle. I was 19, in 1993, at the time and paid $145 for a beat up bike but it was a blast.

    Sent from my VS985 4G using Tapatalk
  10. FJ_Kevin

    FJ_Kevin Been here awhile

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    Welcome Grinder... glad to have you join us. Good deal on that 490! I was working on the YZ490 just tonight. Pulling together more material to post on the race and the bikes. Hope to post more this weekend.

    Since I don't have anything at the moment, I'll re-post this holiday photo, :-)

    [​IMG]
  11. PSchrauber

    PSchrauber Long timer

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    Mmmh very sweet a Bultaco Sherpa model 199b the nicest and latest model build.
  12. FJ_Kevin

    FJ_Kevin Been here awhile

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    Some more from Johnny B.

    This is Rex with his Husqvarna. Rex is recovering from knee replacement surgery and brought out his Husky for all to enjoy even though he could not ride that day.
    Rex has his Husky outfitted with a nice array of vintage endure gear, have a look.

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    Then there is this nicely restored (I'm guessing) '79/80 WR250?

    [​IMG]
  13. FJ_Kevin

    FJ_Kevin Been here awhile

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    I think this is TS250. The guy who owned it could really ride it too. I think he won the vintage class :-)

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  14. Scootern29

    Scootern29 Long timer

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    Hodi Ho!!!!!
  15. Michael N.

    Michael N. Adventurer

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    Does someone know the gear ratios of the 5 speed YZ 465, the IT 465 and the 4 speed YZ490?
    I searced on the web but didn´t find anything.
    I want to compare thr ratios to know what will happen when i swap the whole tranny.

    In fact i definitely didn´t use the 1st gear of the yz465, even starts are better in 2nd gear.
    i wonder if the 4 speed yz490 transmission is better for an average MX rider?

    And one thing left... how can i post pictures here?

    Thank you, Michael
  16. Michael N.

    Michael N. Adventurer

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    Hi, it´s me again...
    Maybe i was a little to reserved with informations abour myself.

    My name ic Michael and i´m new here.
    I live in Austria (Mozart, no Kangaroos) :-) and ride Motocross and Enduro since 2009.
    I started with a Honda CRF 250 from 2006, then owned a KTM EXC 250 from 2010 and traded a
    KTM SXF 350 from 2011 for a Downhill Bike :imaposer, was quier a bargain!
    Long before that time i rode a Superbike on the Racetrack and on the street.
    I run a bicycle store here and was into mountainbike downhill racing for several years, competed
    successful in national and some international races.

    Now i found my love in form of a Yamaha YZ465 from 1981, the US version.
    I had the possibility to ride a 250 YZ from 1980 last year, liked it a lot and this year september i
    got the 465.
    After one race i decided to keep it and started to restore it.

    Here is the YZ 265...

    XZ250.jpg YT250 Ajka_2.jpg

    This is the YZ 465:
    20151003_085635_HDR[1].jpg


    First thing was to change the shock and rework the front suspension, the rear shock
    was changed for an Ohlins and the fork got the Race Tech Cartridge emulators, new seals and bushings and new springs.
    The shock works great and the Race Tech parts are really worth the money, i have a working compression damping now.

    Shock:

    20151027_103354.jpg

    More of the Forks Tuning to come...

    20151030_082409.jpg


    Ride on, Michael
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  17. Michael N.

    Michael N. Adventurer

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    As i told.....
    The race Tech Gold Valve is about to be installed....

    You need to drill the compression holes of the damping rod to a larger diameter and
    deburr them carefully.
    Then you make sure that the Gold Valve settles right on the damping rod and reinstall it.
    The tricky thing is to make sore that it seats proper, itßs only held in place by the spring.
    I had some issues to keep it in place while getting the air out of the (now emulated "Cartridge").
    When compressing the fork and the oil lifted the valve from it´s seat because at this time
    there is no spring to keep it where it should be.
    I helped myself with a vacuum pump from the shop. (yes, we use vacuum pumps to
    custom fit cycling shoes).
    Sorry, no pictures of that but it´s easy to do.
    Fill the fork with oil, close the top cap and rwmove the valve insert.
    Connect the pump to the fork with an adapter or just with a matching hose and a
    hose clamp.
    Then switch on the pump and wait about ten minutes.
    Done. No more air trapped in the oil and the Cartridge.

    20151029_153606.jpg 20151030_082325.jpg 20151030_082355.jpg

    With the screw on the emulator you can adjust the compression damping of the valve, not so comfortable as with modern forks but it works great.


    Before i forget it:

    Could please post someone a picture of the frame of a YZ465 from behind and a little above?
    Mine seems to be bend at the subframe section and i want to see how it shoud look
    right.

    My frame:
    20151113_140602.jpg




    Thanks a lot, Michael
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  18. wfopete

    wfopete Suffer Fools; Gladly!

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    Smart move addressing the suspension with a new shock. The vac pump technique is interesting. Did you replace the fork springs or did the YZ have new springs installed? If the springs are OEM, they are probably junk. I found that unless you have the fork sprung correctly the riders wieght the RT emulators have little effect. If your REALLY serious about your frame take it to a frame shop. I'll bet almost 100% of 465s out there have a tweaked frame to some extent.

    Here are some gear ratios but the numbers don't look correct to me. Maybe they were calulated with different methods. I think I got them out of old magazine test.

    YZ 5:63:1, 4.60:1, 3.46:1, 2.75:1, 2.19:1 14//46

    IT 2.67, 1.75, 1.32, 1.00, .79, 14/44
  19. Michael N.

    Michael N. Adventurer

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    Hi Pete, thank you for the ratios.
    They really seem to be calculated in a different way.

    I try to figure out how.

    I also changed the springs in the fork too but i will try to go with the stock ones too.
    The problem with a bike of this age is that you never know if the springs are stock or not...
    Did you try to increase the damping behavoir of the valve with the screw?

    The Ohlins shock is good but i think the spring is a little too hard.
    I will fit the original one, progressive wound spring from the stock shock when the rebuild is done.
    The stock shock also gets a rework, i will try to do it myself and add an adjustable compression damping too. But that´s a future project....

    If you have an old fridge then you can easily build your own vacuum pump, it is very helpful with
    fork issues.

    The golden Can looks nice on the bike... :) 20151030_082021.jpg

    Cheers, Michael
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  20. wfopete

    wfopete Suffer Fools; Gladly!

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    My personal belief is that your suspension goal is to have "balance" between the front and rear. Set the rear sag and adjust the front end to match it as best you can. I think you want around 1" (25mm) to .5" (12mm) of preload on your fork springs. Then dial it all in for your riding style and terrain. I have not tried to adjust the RT valves yet until I get the correct fork springs for my weight. Those RT valves are a pain to adjust but at least you can adjust them.