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Sport 1200 Misfire/Surging

Discussion in 'BNS12 Chat & Tech' started by Crispy Crouton, Mar 17, 2017.

  1. Crispy Crouton

    Crispy Crouton Just got it firing!

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    Hi all

    I have just dusted off my 2015 Sport 1200 8V after laying up over the winter. Charged the battery and took the bike for a spin. All seemed well and she behaved as normal at speed. However, after about 15 minutes riding I came to a junction and as the bike went to idle it seemed to have what I can only guess as a horrible misfire or surging. It was so bad that I stalled twice pulling away. I thought the bike was going to die on me. Anyway, I gave it a few more revs and pulled away. When I got up to a few thousand rpm and upped the pace the bike seemed as normal until I came to the next junction and the same problem of very rough running at idle. The bike seemed to be 'hunting', a bit like one of those old fashioned lawnmowers! As I mentioned earlier, at speed the bike pulled as impressively as usual, it's just at idle that the misfire/hunting/surging occurs. Any ideas?

    Cheers, Shaun
     
  2. john zibell

    john zibell Moderator Staff Member GT Founder!

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    Check the spark plug caps for arching. If you see a white spot on one of them replace both. Search the forum for the NGK replacement.
     
  3. kiwi croc

    kiwi croc Tuned and Synch'ed

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    A friend of mine had the same sounding problems you mentioned and it turned out to be a faulty ( TPS ) throttle position sensor.
     
  4. Oz1200Guzzi

    Oz1200Guzzi High Miler

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    Also check the stepper motor - drip some carb cleaner into it - sometimes they gum up, likely over the winter break.
     
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  5. Crispy Crouton

    Crispy Crouton Just got it firing!

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    Thanks all. That's 3 things for me to check when I get back from holiday.

    Tony, I've never heard of a stepper motor before. Can you tell me where to locate it on the Sport? Many thanks, Shaun.
     
  6. john zibell

    john zibell Moderator Staff Member GT Founder!

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    Crispy, almost impossible to see. Best way to get carb cleaner to it is through the airbox. Lift but don't remove the tank completely. (I place it sideways to have access.) Remove top of airbox. On the right side near the back on the bottom of the airbox is the hole that supplies air to the stepper. Spray some cleaner there. Start the bike and add more. That should clean it out.
     
  7. Crispy Crouton

    Crispy Crouton Just got it firing!

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    Hi all

    Just to let you know my progress. Got back from holiday and did as Tony and John suggested with the carb cleaner into the stepper motor tube. It took a while but I found it eventually. Seems to be a lot better after a run, so I think it's worked! Fingers crossed! If it goes wrong again I'll let you know. I might replace the spark plugs and caps anyway as the caps are the original rubber type and opinion seems to suggest it's a good precaution.

    Out of interest, is it worth adding one of those injector cleaner treatments to the petrol? I'm sure the handbook probably says not to but that may just be for the sake of warranty. Typical that the bike started playing up literally the moment the warranty expired....

    Anyway, many thanks for all your advice on this. Much appreciated!
     
  8. john zibell

    john zibell Moderator Staff Member GT Founder!

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    Injector cleaner wouldn't hurt and may help.
     

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