What Jet People running in Coloado?
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  1. #1
    Member junk munk's Avatar
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    I'm curious what size main jet you guys running in colorado. I'm in Denver. Figure I'd ask before buying a jet



    Thanks,

    fletch

  2. #2
    Senior Member demarko69's Avatar
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    What ever you do, dont do the following:

    a. Ask Qwerty

    b. Search this forum

    c. Read the pinned post on how to tune a carb.



    Save your money, Denver is the mile high city. Stock will be very close. Maybe even perfect for the newer tw'2.

  3. #3
    Banned qwerty's Avatar
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    Run the right jet for your engine and operating parameters.




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  5. #4
    Member junk munk's Avatar
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    OK, I was just looking for what others had found to work best for them in Colorado. I just figured someone could say "oh yeah, I tried a 115, 120, 130 and a 135, but the 120 worked best for me in Colorado". Since, several people on the site live in Colorado. I was just looking for a better starting point then buying 5 different jets.



    1) I have read defiantly enough not to ask Qwerty, or get slammed



    2) I have surfed the forums of this new site and the old one Google brings up. This site is why a bought a TW in the first place.



    3) I have read the pinned carbing by qwerty under technical help (which is great)



    Anyways the engine pings and pops on deceleration and it has the stock 125 in it, so it is lean I assume?

  6. #5
    Banned qwerty's Avatar
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    AH-HA! Now we have a sympton to diagnose. Popping on decel is too lean. However, if no other symptons are present, you might not even need a jet in Denver, especially if you often head uphill from there. Maybe go ahead and put a washer under the needle and open the pilot screw 3/4 turn, then let us know how the bike responds to those changes.




  7. #6
    Senior Member demarko69's Avatar
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    x2 qwerty, as usual he is spot on



    decel meaning the throttle is closed- indicates pilot 'idle' circuit- could be dirty/clogged or needs adjustment

    do the simple first, adjust the pilot screw, and run a few onces of seafoam in a tank today and report back,

  8. #7
    Member junk munk's Avatar
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    Sounds good, I'll do that today and get back to you.



    Thx!

  9. #8
    Senior Member demarko69's Avatar
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    if the pilot screw has not been previously adjusted you will have to remove the little plug.

    if you can get to the pilot screw I would turn it closed then couunt three full turns open. ride for awhile.

  10. #9
    Member junk munk's Avatar
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    I tried 4 different jets, all could find is Precision (A jets that are marked by cc. Well, the one that felt really good was a 120, would this make since due to being higher in altitude to go down a jet size? A new plug looked the best with this jet as well. I put one shim under the needle and it seems the surging is still there just alittle. I then opened the screw under the small metal plug by one turn. The factory it was set to one turn out, so now it is at 2 turns out. It starts very easily and doesn't die if I bump the gas when it is cold. Would this bea goo spot to call it good? I am going to keep an eye on it over the next couple days and do some more plug chops when more plugs come in in a couple of days from the auto part store.



    Thanks for the help

  11. #10
    Banned qwerty's Avatar
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    Plug chops are a waste of time and money and money. Twisting plugs in and out of a hot aluminum head is begging for messing up the threads.



    I don't give advice on non-Yamaha jets. You are on your own. I would expect a #120 Yamaha jet to be a bit lean at 5000 feet. If the bike has a rideability problem due to carb tune, fix the rideability problem. If there is no rideability problem, no sense fixing what isn't broke.



    Tune one thing at a time. Which of your changes affected the surge problem? If you tune one thing at a time, you know. If you mess with all at once, you don't. That is why it is so important to do one thing at a time. Main jet first. Needle second. Pilot last. Yes, it is a pain in the ass. Most people are too lazy to tune by symptoms, but every racer does. Therefore, most people never learn to tune a carb.



    If you still have surge, there is room for improvement. Keep tinkering.



    At what cruise speed does your engine surge?




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