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Picking your brain

Discussion in 'The Garage' started by Chubby guy 53, Oct 10, 2021.

  1. Chubby guy 53

    Chubby guy 53 XS650 Addict

    Installed Hugh’s ignition new tcbros carbs runs like shit any idea what to try to at least get it to idle so I can set timing lots of backfire
    Adamc likes this.
  2. Gcraay

    Gcraay XS650 Addict

    Backfires are often tied into too lean a gas mix. New carbs don’t mean they’re tuned to your bike. Check your carbs first. Even when they say they are set they’re not always. Turn down the gas on the carbs as much as you can then start slowly bringing it up to find the sweet spot.
    AjD and Adamc like this.
  3. 650Skull

    650Skull SSSSSSSSSlither Top Contributor

    Need to know more information..........What is the ignition system you bought.............if you bought Hughs CDI and PMA then your problems could be timing causing the backfiring if the tiiming marks were off when PMA installed.

    Read what Griz posted this morning.........
    Post #8............. https://www.xs650.com/threads/calling-5-twins-need-jetting-help.60666/
    According to a 1998 poll taken by the American Association of Shadetree Mechanics, 20% of carburetor problems were traced to compression issues, 5% to cam or valve train, 70% to the ignition system, and the rest to the carbies. You gotta have fire to burn the fuel!
    grizld1, Scripto VU and Adamc like this.
  4. grizld1

    grizld1 Grumpy old man Top Contributor

    This is why we make one change at a time whenever possible.
  5. AjD

    AjD XS650 Member

    Have same.set up here. Hugh's ended up sending me a new cdi after we discovered it wasn't advancing.

    Tc bros says the give u a rough tuned carb but u need to do adjustments. I discovered there pilot jet 17.5 is to small and runs really lean.
    Adamc likes this.
  6. jetmechmarty

    jetmechmarty Project collector XS650.com Supporter Top Contributor

    There might be some clues here. He mentions stuff like "designed for two stroke."
    Adamc and AjD like this.
  7. AjD

    AjD XS650 Member

    Upsize your pilot jet a bit. Go like 5 Sizes bigger. When I bought TC's carbs biggest pilot jet they give you for the 17.5 and they don't account for elevation I went to a 22.5 just to get the bike to idle right depending on where you are and what your elevation is your needs are going to change I for example I'm at 500 ft above sea level.
  8. 650Skull

    650Skull SSSSSSSSSlither Top Contributor

    Chubby hasn't raised his head since posting his question
    AjD likes this.
  9. Adamc

    Adamc XS650 MEDDLER XS650.com Supporter

    Gratitude.......it’s a nice word!
    teamWicked and AjD like this.
  10. teamWicked

    teamWicked XS650 Addict Top Contributor

    Gratitude is from the rest of us lurking on the sidelines gleaning a hint of your hard-earned wisdom. When I get another ride on my Tracker I may have some observations on jetting deficiency. I seem to " burbble" at part throttle 25 to 35mph. I can formulate my impressions with more saddle time.But, until I post a question, please get on with your lives.. These responses so far have me studying and thinking.
    Adamc likes this.
  11. Adamc

    Adamc XS650 MEDDLER XS650.com Supporter

    A fair response teamWicked, but that comment wan't aimed directly at you or anyone really. When help or advise is freely given, a word of acknowledgement goes a long way.:)
  12. gggGary

    gggGary On the road of life I'm a speed bump. XS650.com Supporter Top Contributor

    The first post is not conducive to detailed answers for several good reasons
    Adamc likes this.
  13. 650Skull

    650Skull SSSSSSSSSlither Top Contributor

    I was having a bit of fun with this statement. Was in part only, to the time frame.............bigger part was chubbies head................puns intended
    Adamc likes this.

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