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2010 Hyosung GT650 misfire and stalling when hot

Discussion in 'Technical and Troubleshooting Torque' started by hyo1974, Apr 14, 2010.

  1. Hi Everyone. My first post as a newbie rider but unfortunately it revolves around troubles I'm having with my 700km old 2010 Hyosung GT650 EFI.

    Firstly, I really like this bike. I wouldn't have bought it otherwise I guess. I did buy it after being recommended it by two guys I know who have them and were really happy with their Hyos and still are.

    Ok, this is where it's at. I run BP 95 as a fuel. That's about all the influence I've had on the machine. It has travelled 700km but this problem started at the end of my first ride. Starts cold perfectly every time. Runs perfectly cold and on the warmup stage. Go for a ride through average city traffic for about 20-30 minutes and then the gradual misfire starts to creep in when idling at the lights. When you pull up to a stop and idle for anything longer than 20 / 30 seconds it would misfire once, then again, and then twice and if you don't blip the throttle it will eventually misfire so baldy it will stop. Three times it has backfired through the airbox and stalled when I blip the throttle to keep it running. I stopped in a back street and tried to get my phone out to video record it but it stopped dead before I could get the phone out.
    It has had the TPS adjusted and 5 minutes after leaving the repair centre it started again. Exactly the same - no difference at all. Idle speed is normally 1300-1400rpm. I was told that the idle speed is controlled by the ECU and cannot be adjusted.

    The dealer has been really good letting me come in straight away to have it looked at and explained to me what the various parts do etc etc.

    But I am really dissapointed how motorcycling has started out for me.

    I was wondering if anyone else has the same model bike and the same problem and if you have had any joy fixing it?

    Cheers and thanks.
  2. Definitely something not right there. As you have been told, the idle speed is controlled by the ECU. I can't see how the idle speed could be causing backfiring. I would suggest taking the bike back to the dealer and telling them that you don't want the bike back until it is fixed. Sounds to me as if there is something not right with the timing. If they have it in their workshop they can start it when it is stone cold and see how it then runs as it warms up and spend time on the bike.

    I would be very careful riding it too much, would hate for you to take off from an intersection and then have it backfire and die and someone run up your rear.
  3. calling stigger :)
  4. Warranty time, make them find the issue.
  5. Hi there Trekka273,

    It has never stalled on me when trying to take off from the lights or anything. Only when idling. When it does stall during idle or after the backfire or frontfire whichever way you look at it it will start straight away or pretty much straight away. I have seen things on other posts on this forum and others and things range from coils, to stators (alternators??), to throttle body balance, TPI positions, computer reflash - stuff like that.

    I agree, the Minister for War and Finance (Wife) agrees also that I should take it back and leave it there until it is what a new bike should be like.

    But if anyone has had similar experience with this particular model bike please let me know how you go on.

    Cheers and thanks. :)
  6. Just do a search for hyo on the forum you will find lots of posts regarding their build quality.
  7. Good to see that Hyosung is improving finally...

  8. Yup, I did spend an hour or so repairing a kinked air hose from the airbox to the air injection device, pinched wiring (not damaged but left as is would have been bad), rerouted wiring so it not flapping about (I used to build Heavy Trucks so automotive wiring and hoses are nothing new to me) and readjusted the fairing fit. I'm not knocking the Hyo as I like the way it sounds (when it is on song), and the way it rides (looks are there too). It was bought as a commuter bike and that's all really and I sort of knew that I would have a couple of little things go wrong (but on my FIRST ride?). When I bought my 2005 Honda CR-V brand spanking new it had a diff issue and when I worked for Nissan back in early 2000's, a brand new top of the range maxima never made it to Brisbane from the Gold Coast Dealer (50kms I recall) before the engine had a nasty internal failure. So it can happen to anything. I want to keep it as my work bike and am already looking towards my "fun" bike for weekends.
  9. bloody hell dougz, forgot about u, where u been mate?

    try korider.com for hyosung fanatics
  10. Been there but nothining difinitive. Seems there was a EFI system change between 2009 and 2010 and some postings were from people who were giving 2009 EFI fixes for 2010 models so got sort of confusing.
  11. In allhonesty, on an EFI bike it is very difficult to disgnose as it could me any number of things. I haven't really heard of it happening before with car engines, but I guess a throttle position sensor could be the problem, but normally if they are playing up they are all the way through, not just as the bike warms up. Of course, perhaps the heat build up in the sensor is causing the problem. But it really could be any of the sensors... not sure what the Hyo's run, but if they run a MAP sensor it could be having problems, a temp sensor could be sending incorrect signals to the ECU, and it is then trying to compensate by changing timing, etc. Are any of the sensors near the exhaust manifold that you can see? COuld there be a small leak in the exhaust, or poor heat shielding, that is allowing heat on to any of the sensors?

    I wouldn't be playing, it has done 700kms, take it back, and take it back in a hurry. It will not be doing the bike any good to be running like that.
  12. Hi mate,

    I have the same bike and year and it had the exact issues you are describing. I have now 10,000km on it though.

    I've had it in 6 times (i think... stopped counting after a while) for warranty work.

    I've had the fuel pump, regulator/rectifier and stator replaced. One at a time and each making a difference.

    My issue was a little worse than yours. It would cut out under the same conditions as you, but I had another issue. Once it cut out, it would not start until it was totally cold again (forcing me to wait up to 45 minutes). Anywho, that issue was fixed with replacing the fuel pump.

    Your issue with it cutting out at idle has to do with voltage. Most likely the regulator/rectifier. Get your dealer to do a voltage test on that. If your rectifier has been faulty for long then there's a chance it has caused your stator to fry as well. But with so few Kms under that bike's belt it probably is ok.

    My bike used to cut out daily... multiple times. Then to weekly after the rectifier/regulator was replaced. Now after the stator has been changed (again because the voltage was below spec) it hasn't cut out since - touch wood.

    Hope it helps and keep us updated.

    btw, my idle speed is the same as yours. I do however think it is too low. I've got a feeling that the idle would be smoother with iridium plugs.

    edit: let me expand the important bit: get your dealer to test the voltage of the regulator/rectifier WHEN the bike is HOT! Compare to what the manual says.
  13. Hi there,
    Well I went back and the rectifier wiring has been modified to eliminate any voltage drops. I rode back home but half way the same problems are there - unchanged. ](*,)
  14. Warranty issue. There problem to fix, not yours to guess at.

    Start keeping notes though ( how and when it does it, how often you take it in for service and what they tell you after) in case it does develop into a long term saga.
  15. then turn around go back and tell em to fix it properly.
  16. Yeah, believe it or not my bike cut out today again. First time for quite some time. Traffic was stop start for 25km because of an accident just passed where I live. So while I'm not terribly pleased with it I'm not too concerned cause this wasn't usual commute.

    But I will be due for my next service and will make sure they re-investigate. It's definitely a voltage issue and I hear that iridium sparkies arc at a lower voltages than the stock plugs. I happen to already have a set but have been waiting for the dealer to fix my bike properly.

    What state are you in? And if in QLD what dealer do you go to?
  17. It farted and stalled as I was attempting to enter traffic on the way home today, rush hour traffic, uphill grade, just enough momentum to get me partially into the path of the car I DID HAVE enough time to merge in front of. Loaded my pants.:busting:
  18. That is what I was referring to in my first post. Problems like these can come at exactly the wrong time and you can end up in the middle of an intersection and in trouble.

    Take it back to the dealer and leave it there until they fix it. When they tell you it is fixed, take it for a ride and if it happens again, or if there is the slightest sign of it happening again, take it straight back to them. It is a brand new bike, still under warranty, so let them do the work to fix it.

    Be interested to hear what the problem was when it is eventually sorted out.
  19. I have been given a loaner bike for the duration of the repair. It's in the shop now. Damn nice of them I must say.
    Anyhoo on the loaner bike (same but R type) I have been noticing that I am being passed by everyone on the street. Yep, speedo says I'm doing 60 / 80 / 90 / 100 etc but still I'm "holding everyone up". Even Nanna is passing me in her 1984 Corolla!! When I think about it same same on MY bike. I put it down to being cautious. But my Wife was following me home and she said I was on doing 70km/h in the 80 zone near my house. I was definiately doing the limit according to the bike. Strapped on the GPS and guess what - there is a constant 10% speed error in there. ie bike says I'm doing 100km/h - GPS says I'm doing 89.5km/h. hmmmmmm
  20. so thats nothing new, mines out by 8 km/h at 110 according to the gps