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K8 GSX-R750 not always starting

Discussion in 'Technical and Troubleshooting Torque' started by Simon Jones, Sep 1, 2015.

  1. I have a 2008 Gixxer 750, which has started to play up recently. Starts perfectly most of the time, but on occasions it will not start at all. Like the kill switch is on or the clutch is not pulled in.

    If I pull the clutch in and out a few times, kill switch on off a couple of times or key off and on a couple of times, then it starts fine. Could be good for a week or could happen again next time I start it.

    Anyone seen this before, or could think of a reason it might do this? Seems electrical so maybe a contact somewhere, no idea where to look or how to verify?

    All help welcome...

  2. My k8 1000 has an issue with the clutch switch and sometimes wont turn over when u press the start button. I just pull the clutch in and out a couple of time rapidly then try again and it always has started.
    • Informative Informative x 1
  3. ^^Agree.
    Sounds like a switch issue. Does it happen after rain or humid weather OP?
  4. Different bike, similar symptoms - ignition switch "worn" and I was able to build up the worn bit with solder. The hard part was troubleshooting.

    Unless it's a well known bug for your make and model, you'll a circuit diagram, a multimeter and a lot of patience.
  5. Sounds like one of the interlock switches and the Clutch switch is the most likely from what you describe. I don't know exactly for this model but generally there are a number of switches in the start circuit, kill switch, start switch, Clutch Switch, Sidestand Switch, Neutral Switch and a diode block. Any one of these in various combinations can stop it starting.

    From your description it is a switch. Try starting with sidestand down and bike in Neutral and clutch out. Gixxer experts does that combination generally work. I can't find a wiring diagram.
  6. Either the clutch switch or maybe the battery is on its way out.
  7. Yes battery is possible. Simon JonesSimon Jones when it cranks does it sound like it is turning over well and quickly RaRaRaRa rather than Raa.. Raa.. Raa..
  8. Clutch always needs to be in to start.
    • Informative Informative x 1
  9. Have you checked for loose wires on the the clutch switch ?
    • Like Like x 1
  10. The gixxers of that era had a know issue with the side stand switch.
    I think grime from the road and chain get's up into the switch and they can wear out. Try troubleshooting that first and if nothing else, give it a good spray with WD40 up into the piston (slider).

    Do let us know how you get on.

    • Informative Informative x 2
  11. Side stand switch is always a prime suspect.

    Also, do you have shorty adjustable levers? If so increase the span as the short span may be responsible for not completing the circuit when pulled in / engaged. It may be at that 50/50 point - engaged / not engaged.

    Eliminate one problem at a time. So when the bike isn't starting do JUST the clutch, or JUST the kill switch or JUST the side stand - not a combination of all.
    • Agree Agree x 1
    • Informative Informative x 1
  12. Hey guys,

    Cheers for the responses. I've checked the movement in the switches for both the clutch lever and the kick stand and they are both good. Managed to replicate it this morning when it wasn't starting, switch "piston" was fully out on both the clutch and kick stand piston.

    Also tried neutral with kickstand up and still didn't start.

    I just tapped the clutch a couple of times and it started. Would give the impression that it's the clutch? I got some WD40 into it so I'll follow through again tonight and see how it goes.

    Bike is in neutral, so my understanding is that the kickstand switch shouldn't care, that's only if it's in gear?

    I'm thinking now that replacing the clutch switch might be a good start, start by opening it up and cleaning it first. Anyone know if a website wit a decent tutorial on Gixxer repairs?

    Cheers again all.
  13. Just get a new switch and be done with it.
    • Agree Agree x 1
  14. Which is a fair comment Nick gsxr750Nick gsxr750 but sounds like SJ is quite keen to identify the problem by troubleshooting - no harm in that either.

    Simon JonesSimon Jones look at gixxer.com there's always pages of info there
  15. Hey Simon JonesSimon Jones it sounds like you're starting to make some headway. Good work. Before you rip apart the switching mechanism, see if you can confirm 100% that it's the problem.
    You may need someone to help with this. Tape (cable tie) the clutch back to the handlebar so that's fully depressed. Then try closing the piston with your finger (screwdriver) whilst holding the starter button. Giggle it in and out to see if you can produce the same problem.

    I also noticed that no one asked if you had aftermarket levers as these can cause issues with the plunger (piston) on the clutch perch.
    Lastly, don't try and attempt the "bypass modification" unless you know what you're doing as this has been know to mess with the power mapping on the ECU.

    • Informative Informative x 1
  16. Good plan, that's my next steps. Had a look around and found some on ebay from the UK, is there anywhere local that will supply some after market parts?

    Thanks NFI, good advise, I'll give that a go tonight for sure! Cheers also for the tip Lionz
  17. NoideaNoidea No aftermarket levers either, still original...
  18. Why buy it from overseas for when the part is only 10.90 here in Australia .
    I buy all my gsxr750 parts from mick hone motorcycles in box hill .
    They have a online fiche part finder for all Suzuki models with price etc.
  19. image. image.
    • Winner Winner x 1