675 Will Only Partially Crank Not Enough To Start

Discussion in 'Technical Help' started by Spikey, Sep 29, 2023.

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  1. Spikey

    Spikey New Member

    Sep 29, 2023
    1
    3
    Manchester
    #1 Spikey, Sep 29, 2023
    Last edited: Oct 2, 2023
    Hi all. Got a 2010 just bought from a chap who gave up on it. It's a low mile 675 in fab nick but he says he parked one day came back a week later and literally no crank and this is the symptom list.
    Key on, wait for full initialisation, pump etc all good. Hit the starter button and a very short crank - not even a full turn and then full ign resets again as if key just on - sounds almost as if the starter is seized up - even with 2 batteries hooked up it get about a half to one turn slow crank. But... Just fitted new battery, starter and solenoid and 2 x new battery leads and the sprag clutch (opened) appears all good and free and kill switch & start button all tested good. Run a lead from batt+ to solenoid/starter connection and all turns over fine. The previous owner even changed plugs/oil as a "hail mary". Engine quite tight on hand crank from rotor but could be just good compression.
    Should state that even with the sprag itermediate gear removed - thus allowing the starter to spin freely - the same symptoms occur ie hit the starter button and the solenoid engages/tries to crank then just a loud DUNK noise - identical to flat battery/knackered solenoid/stuck starter - take your pick, then system/clocks/pump reset. and is NOT hydrolocked.
    Anyone help here folks? Would love to get out for a few rides before winter kicks in here.
     
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  2. Iceman

    Iceman Crème de la Crème

    Apr 19, 2020
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    Hi Spikey and welcome to the forum, first off these engines are pretty much bomb proof, however what you describe does not sound good, take off the cover to access the bolt for the timing check, and try turning the engine over very slow using a good socket and break bar, that way you will see if the engine is turning freely, the story given to you by the previous owner may be of being "economical with the truth", and it may be the person knew more than they are letting on. Before going into more detail of what may be wrong, try turning the engine by hand and come back and let the forum know the result of that. Hope this assists.
     
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  3. Linx

    Linx Well-Known Member

    Mar 14, 2020
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    Stratford Upon Avon, UK
    They symptoms you describe sound like hydrolock. Try it with the plugs out.
     
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  4. andypandy

    andypandy Crème de la Crème

    Jan 10, 2016
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    Never heard of that. How does that pan out ?
     
  5. Linx

    Linx Well-Known Member

    Mar 14, 2020
    197
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    Stratford Upon Avon, UK
    It's when fuel or coolant seeps into a cylinder. The massive increase in compression means the starter motor can't turn the engine over. I'f you force it, you usually bend a con-rod :confounded:
     
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  6. Spikey

    Spikey New Member

    Sep 29, 2023
    1
    3
    Manchester
    Thanks for reply guys. The motor will spin by hand - so no hydrolock, the motor will also spin over if solenoid jumped directly from battery on the + side and then 2 x earth checks 1 from batt - to frame earth and 1 to engine thus eliminating broken earth wires. So assuming motor is still good. Which then leaves a very abnormal elect fault???
     
  7. Iceman

    Iceman Crème de la Crème

    Apr 19, 2020
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    It used to happen a lot with early 2 stroke Suzuki's, the problem was the fuel tap drained fuel from the tank to the crankcase, then when you tried to start it the engine was effectively Hydro locked, the result was damaged conrods, it happens in more modern machines when the head gasket fails and leaks water and oil to the crankcase, the engine then effectively becomes locked with pressure.
     
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  8. Eldon

    Eldon Elite Member

    Nov 14, 2018
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    #8 Eldon, Sep 30, 2023
    Last edited: Sep 30, 2023
    I have had similiar in the past with a supposedly good, just purchased, secondhand Transit DI engine. The seller stated in good order when in actual fact it must have been stored somewhere damp and corrosion had set in. Being a diesel the clearances were tight and getting over TDC on that cylinder proved difficult so giving one tight spot per revolution. I took the head off and all was revealed, promptly returning the scrap unit.

    Turn over as @Iceman suggested and report back on the resistance experienced, noting the crank angle if anything untoward is felt ( marker pen on the flywheel). Then repeat with the plugs out and see if the resistance is similar or resolved ;)
     
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  9. Spikey

    Spikey New Member

    Sep 29, 2023
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    Manchester
    Hydrolock is not the issue - read initial post - it is an electrical issue.
     
  10. Wishbone

    Wishbone First Class Member

    Nov 4, 2018
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    Not sure if starter relay/socket was mentioned but it could be that if corrosion on the pins or burned cables?
     
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  11. ManInTheJar

    ManInTheJar Member

    Feb 4, 2023
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    Lots of fail safes in the starter circuit, for example clutch and sidestand switches. There should be a wiring diagram/service manual available online to help find them. By jumping the solenoid from the battery you are effectively bypassing them, locating them and bypassing each in turn might throw up a faulty sensor (some are located in areas where the contacts/connectors will corroded and/ or get dirty).

    The CPS connector is another potential culprit, its connector is hidden on the crankcase below the injectors and is a pig to get to.

    Still on the electrical side, a broken or partially broken wire is another possibility if the jerk of the starter causes it to break contact. The wires running to the side of the headstock are particularly prone to this type of damage. Bridging suspected areas with a jump wire and using a multimeter or test light to check continuity should help.

    If you can't find a wiring diagram, I might have one but would need to check to be sure.
     
  12. speeder

    speeder Noble Member

    Jan 3, 2019
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    Have you tried another solenoid? Sounds like high resistance across the contacts to me, as you said it spins over if you bypass the solenoid.
     
  13. Linx

    Linx Well-Known Member

    Mar 14, 2020
    197
    93
    Stratford Upon Avon, UK
    All symptoms of hydrolock on a modern bike.
     
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  14. Spikey

    Spikey New Member

    Sep 29, 2023
    1
    3
    Manchester
    #14 Spikey, Oct 25, 2023
    Last edited: Oct 25, 2023
    Update
    Got brain box back from testing few weeks past and report was: NO FAULTS detected....so back to square -1...
    All statements as per my orig post above still stand true - and NO for the 100th time - it's not hydrolock!!!!.If you want to educate yourself on REAL hydrolock - look up videos on Youtube for "Rufford Ford" to find what really happens and just how stupid drivers, of 4 wheeled vehicles, can be.
    Main symptom is the injectors are not initialising/getting fuel so somewhere it's lost the signal and now the brain box has been confirmed as good what now?
     
  15. Iceman

    Iceman Crème de la Crème

    Apr 19, 2020
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    Head for the oven
     
  16. Spikey

    Spikey New Member

    Sep 29, 2023
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    Manchester
    I suppose any comment is usefull - but gas is so expensive now....
     
  17. Eldon

    Eldon Elite Member

    Nov 14, 2018
    4,159
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    The gas bill will come some time later so as long as you are effective........
    just saying :joy:

    Fuel pump relay?
    Is electrical supply getting there at all to do the "initializing" ?
     
  18. sprintdave

    sprintdave Nurse,he's out of bed again

    May 25, 2014
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    Oh god, electrics, the devil's work. Good luck.
     
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