Author Suddenly won't start  (Read 13065 times)

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  • Offline zed9   us

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      #50

    Offline zed9

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    Re: Suddenly won't start
    Reply #50 on: Jan 07, 2023, 01.26 am
    Jan 07, 2023, 01.26 am
    *Originally Posted by Smoky [+]
    Yes. Running fine, didn't ride for maybe a week went to start it, nothing. The compression gage even if it's off was still reading consistently across the cylinders 1 and 4 the same and 2 and 3 the same but at a double difference. 30psi to 60psi
    A bike won’t fire with 30 to 60 psi. Not enough compression.
    That’s not your problem. A bike doesn’t go from normal running, high compression, to low compression, overnight. (Only a Harbor Fright gauge can say such a thing). You’ve got a bad connection somewhere.

  • Offline CeeJayTee   gb

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    Offline CeeJayTee

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    Re: Suddenly won't start
    Reply #51 on: Jan 07, 2023, 08.01 am
    Jan 07, 2023, 08.01 am
    Here in the UK some of our tool hire places will hire out professional compression testers for the diyers. Do you have those in the US? that my be your best option.

  • Online 3alfa3   hr

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    Online 3alfa3

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    Re: Suddenly won't start
    Reply #52 on: Jan 07, 2023, 09.03 am
    Jan 07, 2023, 09.03 am
    *Originally Posted by Smoky [+]
    Yes. Running fine, didn't ride for maybe a week went to start it, nothing.

    Did you ride mostly short distances, and with low RPMs? Is petrol you use good quality? Does bike burns oil and/or antifreeze?

    Carbon buildup on valves and their seats (almost always intake) is possible, sometimes stuck piston rings etc.
    If bike ran fine on the last ride, its impossible to have compression that low on all cylinders caused by wear, but there is instances when carbon buildup on valves and piston rings was cause of low or no compression after prolonged pause and cleaning was all it needed.
    What engine oil do you use? Maybe burnt low quality oil was deposited on valves, valves seats etc, got hard over a week of pause and now compression is low because of that.

    Do check compression tester to be sure its reading was accurate.
    Last Edit: Jan 07, 2023, 09.13 am by 3alfa3

  • Offline Smoky   us

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    • #53

    Offline Smoky

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    Re: Suddenly won't start
    Reply #53 on: Jan 07, 2023, 05.14 pm
    Jan 07, 2023, 05.14 pm
    Low compression verified. Not enough for combustion

  • Offline Led Zed 70   us

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    Offline Led Zed 70

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    Re: Suddenly won't start
    Reply #54 on: Jan 07, 2023, 06.10 pm
    Jan 07, 2023, 06.10 pm
    Dang that sucks! We’ll hopefully simple like head gasket or piston rings?

  • Offline Smoky   us

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    Offline Smoky

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    Re: Suddenly won't start
    Reply #55 on: Jan 07, 2023, 07.12 pm
    Jan 07, 2023, 07.12 pm
    Hoping cam chain jumped a tooth. This would explain identical psi on cyl. 1 and 4 ...2 and 3.
    Have done this on a Ninla 400, ( top end work) before. Just more stuff..a lot more.

  • Offline Led Zed 70   us

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    Offline Led Zed 70

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    Re: Suddenly won't start
    Reply #56 on: Jan 07, 2023, 07.32 pm
    Jan 07, 2023, 07.32 pm
    Well good luck and can’t wait to hear what it turns out to be and you get her running soon.

  • Offline Smoky   us

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    Offline Smoky

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    Re: Suddenly won't start
    Reply #57 on: Jan 07, 2023, 11.10 pm
    Jan 07, 2023, 11.10 pm
    I'll keep posting as I go through the process
    Thanks everyone

  • Offline Smoky   us

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    • #58

    Offline Smoky

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    Re: Suddenly won't start
    Reply #58 on: Jan 08, 2023, 06.40 pm
    Jan 08, 2023, 06.40 pm
    Valve cover is off. Timing marks are curiously 180° out from my manual. So I find it safe to assume that my manual must be wrong or more likely I am interpreting it wrong. If the bike jumped time it wouldn't be but a tooth or two off. Gonna have to ponder on this.

  • Offline Zaniac948   us

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    Offline Zaniac948

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    Re: Suddenly won't start
    Reply #59 on: Jan 08, 2023, 07.31 pm
    Jan 08, 2023, 07.31 pm
    Not to insult your skill level at all but did you hold the throttle butterflies open during the compression test? My friend did not do this and it gave him a deceptive low reading. Best of luck with a very weird problem