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Starting Issue

Discussion in 'XJ Technical Chat' started by TMHack, May 29, 2007.

  1. TMHack

    TMHack Member

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    Ok, I finally got my bike together enough to start it up and go for a ride. started right up yesterday the first time I started it. Then when I started it up to take it for a ride it fired a little bit less than a couple seconds and then would turn but nothing. the only way I could get it to start was to take one of the pod filters off and hold my hand in front of the intake, essentially choking the heck out of it. once it is started there is not a problem with it starting. unless it sits for a couple of hours. I haven't synced or tuned yet so I'm hoping this will take care of the problem. I have pod filters on it and a 4-1 exhaust. The carbs have been re-jetted to compensate for this. Just wondering if anyone else has run into this and it wasn't a tuning issue. I will be tuning it tonight hopefully time allowing and let you all know how it turns out. I will also get some pics of the project as it sits now up. Still plan on doing some minor mods and painting.

    Thanks,
    Kurt
     
  2. BlueMaxim

    BlueMaxim Active Member

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    Holding your hand over the pod sounds like a problem getting fuel through the carb or into the carb. This could be a clogged starter jet or low fuel height or even an inclined fuel line. If you have an inline fuel filter I would check it for stoppage and also check to make sure the fuel line is going downhill. If it runs uphill air will be trapped at the top and restrict fuel flow.
    I would then colortune and sync which may be the real problem anyway. Lean set mixture screws will cause this problem.
     
  3. RickCoMatic

    RickCoMatic Well-Known Member

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    Pods & 4 - into - 1 Mods.
    You got some tuning to do.

    Holding your hand over the INTAKE?
    Choking it ... really choking it!

    Way too much air happening!
    The unpleasant situation of tuning Carbs, seemingly designed to operate within a narrow window of total Cubic Feet per Minute of fresh air intake ... to run having the restricted fresh air flow removed.

    You have to "Play with it!"

    My personal opinion and a possible solution.
    Measure Max Fresh Air Intake CFM at Airbox solo Intake inlet at 6,000rpm
    Divide by 4.
    Quotient is CFM for individual Carb.

    Fabricate a "NASCAR-Type Restricter Plate" limiting the Individual Carb Fresh Air Intake CFM to within (single digit %) of the design parameter.

    Attempting to Jet to the unrestricted air flow is an endless trial and error situation with lean mixture complications never ending.
     
  4. Hired_Goon

    Hired_Goon Member

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    I have a bike that was hard to start cold but ran perfectly once started.

    Nowadays it starts every day first time without fail.

    The only thing I did to it was review my starting procedure. Most of my bikes require a little throttle to get them going but this one will not start if I crank open the throttle even a tiny bit.

    Pull the choke out and try cranking it over without touching the throttle. Worked for me and I put it down to having pods on. Essentially opening the throttle while starting is letting in too much air and not enough combustable fuel. With the butterflys closed it is getting the correct mix of air fuel to start.

    If this doesn't work then you definately need to look at tuning/jetting carbs.
    With pods and 4 to 1 pipes I went one size up on pilot jet and one up on mains. I need to go up another one or two mains still.
    A well tuned bike should fire up without cranking the gas.
     
  5. Fraps

    Fraps Member

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    What did you do for jetting? How far off stock did you go?
     
  6. TMHack

    TMHack Member

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    From the sounds of it so far m first assumption of tuning it should help. Now I just need to find time. maybe tonight. I tried starting it this morning without touching the throttle and having the choke on full blast and it started up but hard so I'm assuming that there is too much air and not enough fuel going in at the moment. Checked the fuel line and it is going down the whole way, no humps or elevated points.

    As far as jetting I used a Dynojet kit and only changed the main jets and needles. I believe they were 140's and the needle was set to the second groove from the top. Not sure what the stock ones were. These are the Mikuni carbs that came on the bike. I cleaned them the end of last summer.

    I will try and get tuning done tonight and see how well I can get her purring. This will be my first time syncing so wish me luck and patience.

    Thanks for the thoughts. I love the site and have gotten a lot of great things out of it already.
     

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