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  1. #1

    1200LTD 1.2 n/s Stock Pop-off pressure?

    I tried to search for the spec, but I really couldn't find it. Can someone tell me what the pop-off pressure should be on a stock 2000 Yamaha XL1200LTD? This is a power valve motor. It appears like my carbs have been rebuilt before and it seems like the springs are all different. The n/s is a 1.2

    Not looking to hot rod the ski, just return her back to stock.


  2. #2

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    go to the how to section & look at fercho's thread it is one of the top threads, you should find it in there

  3. #3
    Moderator OsideBill's Avatar
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    I got 82 psi on the ones I tested 1.2 N&S and gold 115gr springs
    Last edited by OsideBill; 05-10-2009 at 04:14 PM.

  4. #4
    I put the black springs from the WSM rebuid kit in the carbs. I get about 50psi, 48psi and 54psi pop-off from the three carbs.

    Is a pop-off lower than the 90 psi stock bad? Can it hurt the motor? Will the performance suck?

  5. #5
    Moderator OsideBill's Avatar
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    You want them pop at about 82 PSI for stock the black springs are no good you need gold it will open early and cause you to load up

  6. #6
    Sound like I need more pressure. The WSM carb rebuild kits are unimpressive. I'll throw the gold springs in next.

  7. #7
    Moderator OsideBill's Avatar
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    Never would use them, same goes for SBT. I only use Mikuni parts, it was engineered for the carb originaly.

  8. #8
    Ok - I put the gold springs in an I get 80psi, 80psi and 82psi in each of the 3 carbs - I don't think I can get closer. Confirmed the arms were even with the carb bodies and threw 'er back together. Crank it up and it sounds goooood. No lag and quick snap. This is a rebuilt engine so now it's time to water test.

    So for the next person looking for the pop-off pressure for a Yamaha XL1200LTD power valve, use the gold springs and you should get about 82 psi.

    Thanks for the help. I may be asking more questions after the water test.

  9. #9
    Moderator OsideBill's Avatar
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    That will be fine for stock carbs, make sure the accel pump is funtioning too. I put some wd-40 in it and make sure it pumps out the spray nozzles in carb 1 & 3

  10. #10
    You must have been in my garage! - Yep, sprayed down the linkage and the acc pump with WD40. Everything seems to be working.

    Newbie question - why do they only spray #1 and #3 with the accelerator pump? What's wrong with #2?

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