1982 YZ490 trail machine

Discussion in '2 smokers' started by mudmantra, Sep 28, 2013.

  1. mudmantra

    mudmantra Been here awhile

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    I've got the YZ490 running pretty good. I really like the bike and the power, but I think I need to smooth it out a little bit. I need a some idea's on how to make it better for riding in the woods. What are the best mods for it? Carburetor, Pipe, Ports, Flywheel weight, Gearing? Any idea's, or experience's of turning up the old YZ490 would help. :beer
    #1
  2. advNZer?

    advNZer? Long timer

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    i would suggest a 490 isnt a woods bike?
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  3. Twin-shocker

    Twin-shocker Long timer

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    Why not sell it and buy a 200 of some sort? Using large capacity bikes for competitive woods riding is a bit like choosing a chainsaw for delicate work with wood.
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  4. tHEtREV

    tHEtREV Captain Awesome... tEAM iDIOT.

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    IT490 fly wheel and cylinder maybe?

    Fly wheel weight and a smaller carb.

    No experience with them, just wanted to add something more than the "sell it and by something else" that seems to be popular with some members these days. :lol3
    #4
  5. Twin-shocker

    Twin-shocker Long timer

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    Its very easy to spend a lot of money trying to change an open class MX bike into a capable woods bike. Its possible to improve it certainly, but it will never be as good as a smaller machine. When you figure in the cost of the alterations, selling and getting a more suitable bike seems the best way to go for most.
    #5
  6. anotherguy

    anotherguy unsympathetic

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    Send the cylinder and head to Eric Gorr. viola! Broad smooth reliable powerband with enough power to scare anyone with sense.
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  7. Twin-shocker

    Twin-shocker Long timer

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    I wonder if the power of an open class MX bike is ideal for competitive woods riding? Guess it might piss the open class rider off a little if he keeps getting smoked by someone on a well ridden 125......................
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  8. mudmantra

    mudmantra Been here awhile

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    I tried some newer machines. They just don't have any charisma. This machine well be set up for having fun, not racing. But I may find a 200 I like someday. :1drink
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  9. mudmantra

    mudmantra Been here awhile

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    Thanks. I looked into it. Would be cool, but it's the crankshaft that's heavier on the IT490. It would be a lot of work, but I might try it some day. I just got a stealthy flywheel weight, it should give me a good idea of what to expect.
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  10. mudmantra

    mudmantra Been here awhile

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    Thanks, I think I'm going to do that. I was going to say more low end and mid range power. But how much can you really use? More and smoother would be excellent. :thumb
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  11. Twin-shocker

    Twin-shocker Long timer

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    Years ago I had a ride on an ex works Jawa ISDT bike, think it was around 420cc. That pulled like a trials bike on steroids at low speeds, yet was very very quick as soon as the throttle was opened. The porting on an open class MX bike is all wrong for that sort of performance, although I would guess could be altered to suit woods use much better.

    Try an older KDX200 if you can.............very surprising little bikes, and pretty much bulletproof in terms of reliability.
    #11
  12. dhallilama

    dhallilama Long timer

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    for just having fun, not competing? i'd say the 490 could be a effing hoot.

    i had one that was my primary off road bike... tight single track, mountains, woods, desert, sand, snow, everything. it was a very fun all-around bike. it wouldn't have been competitive in the tight stuff, but i wasn't competing... it was still fun. in the open stuff? it was a monster and competitive. the bike, that is... the rider (me) fell off too much to be competitive.

    i sent the jug/head to Eric Gorr for the "head mod" and stated that i wanted low rpm grunt. what i got was a much, much easier starting bike, easy to jet, didn't ping, lugged like a tractor at idle and would rip when demanded. there wasn't a huge hit when it came on the pipe... just more and more thrust feeling.

    the forks had race tech gold valve cartridge emulators, sent the rear shock to race tech for their treatment (seem to remember that costing around $500, years ago).

    i put an IT flywheel & stator plate on it, a headlight & tail light. don't remember if it was just a drop-in affair or not...
    i even rode it on the street reasonably often (usually just connecting trails).

    there are bikes of the same era that are way, way easier to ride in the tight stuff (IT175 comes to mind)... but there's something to be said about coming to a clearing, cracking the throttle open and hitting warp speed while throwing a roost of rocks the size of softballs as you hang on for dear life, grinning from ear to ear.

    damnit, i'm gonna go find another 490 now...
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  13. anotherguy

    anotherguy unsympathetic

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    Twin Sucker seems unable to see others may want something different than he does.

    Sending the top end off to Gorr will result in a nice rideable albeit fast motorcycle. However do not skip suspension set up. As power levels go up it tends to magnify suspension shortcomings. At the least springs to suit weight/use if not mods like the aforementioned cartridge emulators. I have them in my 465 and big improvement. In fact the 43MM forks are from an '82 490.

    Enjoy and post up the results.
    #13
  14. dhallilama

    dhallilama Long timer

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    ok... not a 490... and a '77 so i've got all sorts of yamahop/horrible rear suspension... but i got around the squishy forks and SLS drum with a USD fork swap from a late model YZ450f

    [​IMG]


    got the forks used, cheaper than gold valves would be
    #14
  15. mudmantra

    mudmantra Been here awhile

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    Cool. :bmwrider What year was your YZ490? I had to fix the wires on my stator to get it to run right at first. The 1982 stator/ CDI type is the same as the IT490, only the IT490 has a lighting coil. So yes it would be a drop in mod. My YZ490 had a lighting coil and lights, when I got it. Did your YZ490 have a stock pipe?
    #15
  16. dhallilama

    dhallilama Long timer

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    mine was an '82... stock pipe, stock silencer.
    got it with aluminum renthal bars, replaced them with steel bars filled with lead shot & silicone caulk (drunken idea to kill the vibration... worked pretty well).

    i accumulated a bunch of bikes and the YZ ended up sitting for a couple years. became single & had to sell off a bunch of the bikes, the YZ being one of 'em. it's one that i wish i didn't let go. kept a KX500 instead, that threatened to kill me every time i rode it.
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  17. mudmantra

    mudmantra Been here awhile

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    I have a set of new fork seals. I'll install the new seals and test the forks with some fresh clean fluid. Pretty cool that you can still get improvement parts for them. :thumb
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  18. Mr. Carts

    Mr. Carts Been here awhile

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    I got a 75watt lighting coil from Ricky Stator.

    I have a set of YZ490 forks and a 18in rear wheel buried in my shed. I am not sure what year they are off.

    Would the it be worth the efforts to swap them out on my IT465?

    Thanks
    #18
  19. anotherguy

    anotherguy unsympathetic

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    What year is your IT465? If you already have 43MM forks no gain.

    The advantage of the forks for me was 43MM vs. 39MM. Much beefier. Had to hunt down the appropriate brake backing plate as the brake anchor boss is in a different location on the 43MM fork. Between the size and damping upgrade the difference in handling was stunning. Took that hinge in the middle feeling away and gave a precision feel to corner turn in. In soft stuff I can plow the front wheel and let off just a touch and the bike hooks up and turns. It always turned well with the throttle but now I have a choice of throttle or handlebars.
    #19
  20. Mr. Carts

    Mr. Carts Been here awhile

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    I have the front wheel that came with the YZ490 forks.

    I was wondering about the rear wheel and brake if they will bolt on or will I need to do some modifying.
    #20