1982 YZ490 trail machine

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

  1. mudmantra

    mudmantra Been here awhile

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    :thumbThanks. I'm going to try another CDI I have first. It's going on a first year BW200. It has a CDI that was plagued with problems. I see they might offer a TW200 CDI, that might be close enough to do the job. I read in a cycle test that the 1980 YZ465 CDI was Improved for better starting in 1981. I don't know how true that is. That same improved CDI was used on the 1982 YZ490. My 1980 YZ465 and YZ490 start the same. If you have your act together they start easy, if you don't, you better be ready for some punishment. :lol3
  2. Racerjoe

    Racerjoe n00b

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    Sooo... Have you gotten them back? How did it work? I have a WR 500 that I was thinking about sending.. been reading your thread and wanting to hear the results. :evil

    [​IMG]
  3. Racerjoe

    Racerjoe n00b

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    Oh that brings back memories.... I rode one of those things one time when I was about 17 years old... it was like I could not keep the front end down.. it was plain wild...
  4. tommyg

    tommyg Long timer

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    I worked my way up from a 81yz 80 to a 125, then a 250 all 81 yzs. Used them for trail riding in N. Mi. When I was 20 I figured I was man enough for a used 465, I was wrong that thing hit so hard I found myself on my ass too many times, finally a serious crash with many injuries found it up for sale. Sold to a friend, put him in the hospital first day. Bike made the rounds in my small town, same results everytime. I really miss the 250, great trail bike, wish I still had it.
  5. athomerecords25

    athomerecords25 Banned

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    I have had lots of Porting and Head work done on my bikes by Eric Gorr, and I have always loved how things come back, but I would also love to hear what this poster thinks of Eric's work.
  6. mudmantra

    mudmantra Been here awhile

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    I've got the motor back together. But then I decided to paint the frame. At first I started just doing a section at a time, by sanding and using a wire brush. Finally I just stripped the whole frame and painted it. Next I'll paint the swing arm and shock spring. The porting looks good. I asked for the longer smoother powerband. I also had a compression release installed for easier starting. I have one on my YZ465 and it makes it a ton easier to start on the trail. :evil Picture of painted frame.

    [​IMG]
  7. athomerecords25

    athomerecords25 Banned

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    Thank you for the reply in regards to the Porting. I know that the WR500's only had Top End and the rest of the power range was flat. I wanted to know how the power range was improved, but I guess that answer will come in time.

    What made you choose the Black frame color, instead of sticking with the stock white color?

    Once again thank you for your reply.
  8. mudmantra

    mudmantra Been here awhile

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    It's the frame from my 1982 YZ490. Just about everything is cleaned and painted. Now I'm putting it back together.
    [​IMG]
  9. NortwestRider

    NortwestRider TRIPOD ADVENTURER !!

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    I'm dual sporting a 1983 IT490 right now and this thread has been great !!.


    I know a lot about a few things,a little about a lot of things but I don't know everything about anything !!.
  10. mudmantra

    mudmantra Been here awhile

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    The 490 is back together. Now that the motor has been bored .5mm over, plus the porting and head mod. It's running rich and won't completely clear out. It's back to jetting again.
    [​IMG]
  11. wfopete

    wfopete Suffer Fools; Gladly!

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    Get that timing and jetting sorted out and it's a whole new world.
  12. mudmantra

    mudmantra Been here awhile

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    Thanks. Even though it wasn't running right, I like the way the bike rode in the woods. I brought the bike back to my faster test area and started to work on the jetting. This is the way it was jetted before the port and head mod. Main jet 440, pilot jet 45, slide 3.5, needle jet Q-8, needle 6F16 clip #2, air screw 2 turns out. It felt like it was running rich.
    I tried a #40 pilot and move the clip to the top spot. It ran better down low, but still missed at full throttle.
    I then tried jetting it like my YZ465 400 main jet, 40 pilot, R-0 needle jet, 6DH4 needle #3 clip. A lot more power low and top but felt lean.
    Tried a 430 main jet, it was to rich. Tried a 410 main jet much better, wide open. Tried a 45 pilot jet, still acted a little lean at idle. I might try moving the needle down 1 click, and see how it works.
  13. wfopete

    wfopete Suffer Fools; Gladly!

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    What's your spark plug look like?
  14. mudmantra

    mudmantra Been here awhile

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    Thanks I'll check the spark plug today. I think the spark plug is one or two heat range hotter than stock. I don't know if that would change the way the bike runs or not. I'll get, or order a stock plug today. I also have a couple of iridium plugs that cross over to the stock heat range. I don't remember why I'm not using those.
  15. KX50002

    KX50002 NooB, my ass

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    Plug to hot could cause detonation, very destructive.
  16. mudmantra

    mudmantra Been here awhile

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    Checked the plug, it was medium grey, and dry. Looked a little rich to me. Hard to really tell because all the plug charts I found, I think were for 4 strokes. I installed an iridium plug of the correct heat range. Lowered the needle one click and set the airscrew at 3/4 turns out from closed. It ran at it's best today, but it was raining. I'll check it again when the weather gets better. I also ordered a standard plug.
  17. Norty01

    Norty01 Occupant

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    Try 3 turns out.
  18. mudmantra

    mudmantra Been here awhile

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    I did a bunch more testing, and best running I got was with a Q-6 needle jet, 6F16 needle at #2, 420 main jet, 47.5 pilot jet. Air screw 2 1/4 turns out. Starts good, Idles good with the air screw 2 1/4 turns out. A little lean at idle when it's hot with the air screw 2 1/2 turns out. It runs like a dragster and picks the front wheel up with ease, just rolling the throttle on, in all 4 gears. It still doesn't run as smooth as my YZ465 at 1/4 throttle. It might be impossible, but I'd like to get it to run smoother at just above idle.
    [​IMG]
  19. mudmantra

    mudmantra Been here awhile

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    I turned the air screw out 3, then 3.5 turns out. It leaned the idle mixture out to far, but did slightly improve 1/4 to 1/2 throttle response. I then set it back to 2 turns out and dropped the needle to the top groove. Idle, 1/4 to 1/2 throttle response completely cleared up, but 3/4 to full throttle is to lean now.
  20. KX50002

    KX50002 NooB, my ass

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    Go up one on the main