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Thread: Riddle me this..

  1. #1
    Senior Member 34nineteen's Avatar
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    Riddle me this..

    On my S1 yesterday I finally tried to get it to actually run. Cleaned out the fuel tank, added fresh fuel. Pulled the carb, pulled the float bowl (it was very clean), vacuum slide is working great- someone must’ve rebuilt it before I got it. Checked spark and that seemed ok as well. Battery fully charged.

    Ok, so I went to fire it and it’s protesting and not wanting to fire. Eventually it starts firing intermittently if I hold the throttle open, but it’s only running on 1 cyl. I stop and check the exhaust pipes and both are warm/hot. So, it’s been hitting on both just intermittent and inconsistent. I’ve tried reversing the plugs and wires and the problem does seem to be following a plug or wire as I start “reversing” them.


    What do you think is going on?

    1. Flaky coil
    2. Coil wires breaking down
    3. Cam sensor going out

    It’s not fuel, the garage is full of smoke and reeks of unburned fuel, from the weird ignition. Fuel is fresh and uncontaminated. Fuel hose is not kinked when the tank is set down. I once bought an SV650 for CHEAP that was kinking the fuel line when the fuel tank was lowered, and the owner was beyond frustrated.

  2. #2
    Senior Member Cooter's Avatar
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    Did you pull out the idle and main jet when the bowl was off? I know you said it was clean but the PO may have been chasing a this problem as well.

    More than once I ave been surprised by how BAD todays fuels are They leave concrete hard deposits that a soak in Berrymans won't even loosen up. A cheap set of jewelers drill bits will let you use the appropriate size to clean them out by hand without enlarging them. Might as well run them through all the holes in the emulsion tube as well. A Welding tip cleaner set works ok too, but I prefer the bits.

    That said, if the problem is following the cylinder ignition swap, that narrows it down greatly. That plug wire, the one coil output tower, that plug... Pull one off and try to start it that way. No start means that the wire/plug/tower, starting and running the same mean the opposite one is the issue.

    Sounds like you are on the right track...

    If indeed it is just firing intermittently on both cylinders (warm primary tubes clue) I'd look into the cam sensor. Disclosure: I don't know tubers well... it might have a crank sensor? Whatever it is that fires the coil, or a bad connection between the 2 is what you're looking for.

    Good luck bro. I happen to be in your town until wednesday, staying just south of you in Old Town, Muahahaha. If you want a hand I can try to make some evening free time and swing by

  3. #3
    Senior Member Cooter's Avatar
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    And you BETTER be using JIS screwdrivers!!!


  4. #4
    Senior Member lancruza's Avatar
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    TEMPORARY HIJACK - Cooter...is that Bubbles, Heather Thomas, or WHO IS IT? I can't believe you changed your tar. (Nevermind, I asked too soon. My expertise in research reveals that it is indeed HT. Hmmmm....maybe HT and Bubbles are one in the same.)
    Last edited by lancruza; 07-05-2020 at 09:31 PM.

  5. #5
    Senior Member 34nineteen's Avatar
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    Quote Originally Posted by Cooter View Post
    And you BETTER be using JIS screwdrivers!!!

    Ha! Already converted to allen.

    I do have a JIS screwdriver. Since it was expensive (for a screwdriver) , I rarely use it. I have a homemade one that works just as well... sort of.

  6. #6
    Senior Member 34nineteen's Avatar
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    Nope. The bike was an non-runner when I got it, so anything goes. Supposedly the seller was in the middle of rebuilding it and lost his motivation. He stripped it down to powder coat the frame, supposedly rebuilt the engine, and ran out of gas putting it back together.

    The inside of the carb looked clean, so I think someone went through it already. No gas residue in the float bowl. All jets and passages are clean and clear. The vacuum diaphragm is working.

    The ignition will make spark and it will start and run. It starts pretty quickly but won’t idle and runs like cr@p. I will run better if I hold the throttle open. The spark plugs are new and sort of gapped correctly (.035 instead of .038-.045). The gap isn’t the issue. The problem is that the plugs are not firing correctly. The timing seems right as there are no backfires. It’s just like they start and stop intermittently with a mind of their own. I have been able to isolate a single cylinder not firing, but then it will start firing again. I have pulled the plugs after running the bike and usually one is wet. Probably from not firng. I dry them off and they will fire again for a bit.

    This is a good brain teaser for everyone who has a weird problem with their bike.

    I’ve actually solved it, so she runs now. I just want to see if anyone else can figure it out.

  7. #7
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    Just put new plugs in it. That's the answer for most problems like this be surprised how much time you can waste on something that has ****ty plugs.

  8. #8
    Senior Member 34nineteen's Avatar
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    Already did, and I agree with that. The plugs are brand new.

  9. #9
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    Ok who's next at this riddle lol

  10. #10
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    Hey I just realized I'm a senior member now. Congrats to me. I'm having a whiskey



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