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Breaking Up When Cold

Discussion in 'The Garage' started by Ozboy, Oct 20, 2018.

  1. Ozboy

    Ozboy XS650 Addict

    So the past two trips out the old girl has been breaking up for the first few Kms cold. It starts first kick no choke idles perfect but when i start to throttle up from first to second gear it starts to break up but here is the crazy part after a few Kms it goes away and the bike runs fantastic all ride. Was 100Kms today.
    I think its a fuel issue so took cap off to vent...still there...
    Pulled choke out...still there...
    I have a quality clear fuel filter with not much debris in it...
    Can any one point something out I am missing?
     
  2. gggGary

    gggGary I'm listening, change my mind XS650.com Supporter Top Contributor

    Check floats, float needles? Perhaps a high fuel level? Have you pulled the plugs when it's happening to see if you are rich or lean?
     
    Ozboy likes this.
  3. grizld1

    grizld1 Grumpy old man Top Contributor

    The combustion tripod stands on three legs: ignition, compression, and fuel. Symptoms described aren't likely to be compression related, and the rule of thumb is, "In the absence of evidence to the contrary, troubleshoot ignition first." So: How old are your plugs, plug caps, and wires? Do you still have OE breaker point ignition, and if so, when did you last inspect the points? Are electrical connections clean and dry?

    Edit: Ya need more coffee, Gary! :laugh: The breakup clears when the motor gets warm.
     
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  4. Ozboy

    Ozboy XS650 Addict

    Yeah i am looking at the floats and needles as plugs, leads, caps and coil all near new but not to say there might be a problem with them. It is a TCI. Carbs were off recently and heights were fine unless some binding up.
    Ha ha ha more coffe alright as all the searches i did i didint find much and crazy as hell it goes away for a perfect ride..no back fires, pops, farts, coughs or surges just awesome!
    Just gonna be a throw all my back up parts at it cold until it goes.
    Cheers Gurus!
     
  5. grizld1

    grizld1 Grumpy old man Top Contributor

    Oops, I see that now--Japanese home market model. I'd assumed an Oceania version of the SG (still had points).
     
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  6. gggGary

    gggGary I'm listening, change my mind XS650.com Supporter Top Contributor

    Fully charge the battery overnight see if that changes anything. (weak pick up magnet?) Another test for that is to unplug the regulator for a bit. The magnet is easily checked with a bit of steel to see if it still has good pull. Check and clean electrical connections and switches.
    Doing a wake up on an 81 and the fuse box looks good but almost all the fuse holders were making intermittent, if any, contact.
     
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  7. Ozboy

    Ozboy XS650 Addict

    Battery sitting overnight is 12.5v, replaced fuse box with blade box but will re check all connections. I can pull over and unplug reg/rec and see if that helps. I have fixed my old volt drop issue and got that down to 0.1v from battery to key power on fuse box but i will check brown wire to brushes for drop. Slap test was ok not a huge pull but did pull. I will hook up my volt meter and run with that to see what reading i get.
    Might need to tipple that coffe and make it an Irish Coffee gggGary and Grizld
    Thanks
     
    gggGary likes this.
  8. Ozboy

    Ozboy XS650 Addict

    Yeah 1979 G Japan model so i guess one of the first TCI. It is hard with some wiring diagrams but I go thru different model diagrams to piece it all together.
    I was planning on getting a complete harness for the G but with these differnces it will give me some grief.
    Cheers
     
    Last edited: Oct 20, 2018
    gggGary likes this.
  9. gggGary

    gggGary I'm listening, change my mind XS650.com Supporter Top Contributor

    To be clear the TCI uses pickups that fire when a small magnet imbedded in the rotor passes them. If the magnet is weak the magnetic fields from the charging system can confuse the pickup trigger causing poor ignition. Kind of out there but it's been seen before.
     
    Last edited: Oct 20, 2018
    Ozboy likes this.
  10. 5twins

    5twins XS650 Guru Top Contributor

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    That's odd not to need the choke for cold starts. Most all of these do, even in warm weather for a short time. The motor needs a richer mix when cold, that's the whole point of the "choke". But these aren't really a "choke" that blocks air flow off, they are a little separate enrichening circuit that adds more fuel. Maybe what you're experiencing is normal for a slightly fuel starved cold motor. Try feeding it a little choke when it's breaking up and see if that clears it up.
     
  11. gggGary

    gggGary I'm listening, change my mind XS650.com Supporter Top Contributor

    How do the plugs look? Might have bit of oil passing an intake valve seal while the bike sits causing some oil fouling that gets burned off in a few minutes.
     
    Last edited: Oct 20, 2018
    grizld1 and Jim like this.
  12. Ozboy

    Ozboy XS650 Addict

    5t in the first post i mentioned pulling the choke when it happens and made no difference plus realeasing the cap to vent more. It has been a daily ride latley so I don't need to choke but if i leave it for a few days I will use the choke. Plugs look good and no fouling on them no smell of burning oil or smoke either. I will put some fresh plugs in to see when they read about my mixtures but it was running fine. I am Thinking electrical but those problems are more consistent but fuel is another issue in regards to clearing up in say a sticking float that unsticks.
    Cheers
     
    gggGary likes this.
  13. Superjet

    Superjet XS650 Guru Top Contributor

    Have the temperatures been cooler when thus happened? Sounds like my Roadstar when I leave for work early October here in Canada when temps are around 6 to 8 deg Celcius.
     
    gggGary likes this.
  14. Ozboy

    Ozboy XS650 Addict

    Hey man nope we are coming into spring downunder here and temps were about 24-25c.
    Cheers
     
    gggGary likes this.
  15. Ozboy

    Ozboy XS650 Addict

    So put old working coil on, new plugs still braking up when cold and running awesome when warm. Stoped pulled reg-rec lead still there. Checked all wiring connections so i guess it only leaves me to pull the carbs again and check them out. Might be time to pull the pin on some VM34 f it goes out of whack this quick. All balanced and drop dead test fine idles fine cold too. Just still there throttluing up from 1st to 2nd!!
    Cheers
     

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