Carburator Jetting
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Thread: Carburator Jetting

  1. #1
    Senior Member Tw200quebec's Avatar
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    Carburator Jetting

    I am looking for some infos on how to re jet the carburetor, I know TW are set poor at factory for emission control and when I look at my spark plug, it looks very poor... It was also doing lots of back fires on deceleration so I changed the pilot jet for a 34 and 2-1/2 turns on the screw. Seems to be much better and less backfires... My 2 nd plan is riching out the main circuity (main jet and needle) I ordered a 128 and 130 main jet and asked my dealer if he had the shims for the needle, he is going to get back to me. If ever those shims are not available at my dealer where can they be purchased? My TW is stock, no exhaust, air intake modifications ride pretty much at sea level to 1000 feet. The real question is... This is my second TW and my first was stock other the 2 turns on the pilot screw with stock jetting and nice color spark plug. No back fire and nice color spark plug. My new TW started back firing on deceleration and the spark plug is whitish (poor) can something have broken in the carburetor letting air pass through? The first thing I did was remove the carburetor cleaned it out, adjusted the float level because it was off from the factory... reinstalled and this did not fix the issue, so did the pilot jet modification, bike seems to run good but whitish spark plug... so planning on riching the main jet and needle. Any help would be greatly appreciated. Thank you!
    jtomelliott49 likes this.

  2. #2
    Member raffles's Avatar
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    Quote Originally Posted by Tw200quebec View Post
    I am looking for some infos on how to re jet the carburetor, I know TW are set poor at factory for emission control and when I look at my spark plug, it looks very poor... It was also doing lots of back fires on deceleration so I changed the pilot jet for a 34 and 2-1/2 turns on the screw. Seems to be much better and less backfires... My 2 nd plan is riching out the main circuity (main jet and needle) I ordered a 128 and 130 main jet and asked my dealer if he had the shims for the needle, he is going to get back to me. If ever those shims are not available at my dealer where can they be purchased? My TW is stock, no exhaust, air intake modifications ride pretty much at sea level to 1000 feet. The real question is... This is my second TW and my first was stock other the 2 turns on the pilot screw with stock jetting and nice color spark plug. No back fire and nice color spark plug. My new TW started back firing on deceleration and the spark plug is whitish (poor) can something have broken in the carburetor letting air pass through? The first thing I did was remove the carburetor cleaned it out, adjusted the float level because it was off from the factory... reinstalled and this did not fix the issue, so did the pilot jet modification, bike seems to run good but whitish spark plug... so planning on riching the main jet and needle. Any help would be greatly appreciated. Thank you!
    , check the technical side of threads , there is absolutely every poss concern and things to do/ try on carbs, as there is the old style barrel slide card and the the later cv carb with the round flat dome on there, in my experience you will never get the carb set up 100% but can make it better , another thing to check and is also on forum , air leaks from rubber manifold to cyl head try running bike and spray a carb type product around there if the eng speeds up or runs different that is your first fix before mucking around with carb
    jtomelliott49 likes this.

  3. #3
    Senior Member sibyrnes's Avatar
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    Here's the shims you need. I am running with a 130 main jet and I think 4 shims. Bike runs great!
    https://www.mcmaster.com/99040A310
    admiral, Sthrnromr, jbfla and 2 others like this.

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  5. #4
    Junior Member fagro's Avatar
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    Just did a 34 pilot and 130 main 2 turns of the screw, no shims. What a difference. Starts better, idles waay better. No popping or surging.
    jtomelliott49 likes this.

  6. #5
    Senior Member Tw200quebec's Avatar
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    Quote Originally Posted by fagro View Post
    Just did a 34 pilot and 130 main 2 turns of the screw, no shims. What a difference. Starts better, idles waay better. No popping or surging.
    You running stock with OEM exhaust and air intake?
    jtomelliott49 likes this.

  7. #6
    Junior Member fagro's Avatar
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    Quote Originally Posted by Tw200quebec View Post
    Quote Originally Posted by fagro View Post
    Just did a 34 pilot and 130 main 2 turns of the screw, no shims. What a difference. Starts better, idles waay better. No popping or surging.
    You running stock with OEM exhaust and air intake?
    Yes... completely stock
    jtomelliott49 likes this.

  8. #7
    Senior Member TWBigBlake's Avatar
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    Where do you buy your jets from?
    jtomelliott49 likes this.

  9. #8
    Senior Member Darth's Avatar
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    Blake, I've gotten all my jets from Partzilla.com.

    They were Yamaha OE, discounted from dealer price but the shipping eats that up, and more!
    Their parts diagrams & lists are very useful whether you buy their bits or not.

    Rocky Mountain ATV is a good source for the same stuff. Seems like shipping is a bit less, don't recall for sure.

    The links at the bottom left of this page will lead you to lots of info.
    Look for pro-quality carb photos and great advice from member jbfla.
    jtomelliott49 likes this.
    "Faster, faster, faster, until the thrill of speed overcomes the fear of death."
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    and wad up my bike somethin' awful...
    Still, I rise!
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  10. #9
    Junior Member fagro's Avatar
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    Partzilla
    jtomelliott49 likes this.

  11. #10
    Junior Member fagro's Avatar
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    Quote Originally Posted by fagro View Post
    Quote Originally Posted by Tw200quebec View Post
    Quote Originally Posted by fagro View Post
    Just did a 34 pilot and 130 main 2 turns of the screw, no shims. What a difference. Starts better, idles waay better. No popping or surging.
    You running stock with OEM exhaust and air intake?
    Yes... completely stock
    [QUOTE=TWBigBlake;1000606]Where do you buy your jets from?[/QUOTE
    Partzilla
    jtomelliott49 likes this.

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