Hyosung Cold Start Problem

Hyosung Motorcycle Cold Start Problem – Well, it has been almost 3 weeks now I  am having this problem. Basically, my bike is having hard time to start in the early morning, i.e. Cold start and it takes me about 10-20 minutes to fire it up. However, once the engine is warmed up, the subsequent start fired up without any problems. So the issues is with cold start and not warm start.

I don’t think there is an issue with the battery as the bike is just about 3 months old and  the lights, horn, signal are working in a good condition.

I did not manage to record a video to describe my problem, but upon searching online, I found someone posted a video which the issue is similar to mine. The video can be view below:

*Video credited to the original owner. I do not own the rights.

I’ve read online and there are only two possibilities that I’ve narrowed down. This could be due to Engine Temperature Sensor (ETS) or the Roll Over Switch. (RO).

Today, I took half day and ride my bike to Naza Service Center in Shah Alam. The first thing that they checked is to see if the is any errors via the Hyosung Diagnostic tool as per below.

The good news is, there is no error shown at the ODO meter.

The next step, I insisted them to check on the battery just to make sure it is good and it looks like that is the case. The battery reading was increasing as soon as they Rev the engine at about 5K RPM which indicates both Battery and the Rectifier is in good hand.

They have then concluded that this issue is with the Engine Temperature Sensor (ETS) and it is located at the left side of the engine.

Here is my faulty Engine Temperature Sensor (ETS)

The faulty ETS with the new ETS package / cover. At this point, they have insallaed the new ETS and I got it for free as my bike is still under warranty.

Finally, the ETS has been changed on my bike and the cold start issue seems to be resolved.

If you have any questions, drop them at the comment box below and feel free to share this article via the social buttons.

31 Responses

  1. Zachary Pierce says:

    Im having the exact same issue. But when its in the sun. Sometimes if it just sits for a while. My gears are funny at times. And rpms are not where they should be. I should be getting alot more out of my bike than i am. Its been in the shop 10 to 11 times. Sent to the manufacturers. And about to go back again Should i recommend this? And once you fixed your bike. Did you get better performance? Every blue moon. My bike will run the way it should. I get 10 mph more out of first gear and so on. In 5th gear my rpms will 2000 plus less than than how it normally runs

    • Zachary Pierce says:

      Im speaking of your starting issue in my comment. And also i forgot the word ‘run’ right before 2000 rpms

      • Zachary, if you’re having this similar issue, you can recommend your manufacturer to check on this. As for performance, I don’t feel any differences as it’s just standard parts that I’ve replaced it with. Also, ask them to check on your plug caps (both) and see if there are any cracks?

  2. Mokoera Te Amo says:

    Thanks for the information bro. Is this solely for efi models or would this be the case for carb’d models too. Regards

  3. Pyro says:

    Hi there…is these problems also as Hyosung Exiv GD250n?

  4. Pyro says:

    Hi there…is these problems also as Hyosung Exiv GD250n?

  5. HamZa NiZar says:

    hi i m hamza i want to thank you for this website to help the hyosung riders

    so, i have a gt 250i model 2012 19 000kms my problem is the engine can not take the stable RPM (1,5*1000) on my engine sometimes he accelerate automaticly so i cant ride on low speed (2*1000 or 1*1000 and the engine switsh of if i don’t give gas), the engine can not take the diet
    i’ve clean air filter, and the tank gas, and i’ve put the additive with gaz to clean the injectors, ive changed the IAP NO 1 and ive changed the candle for new 2 ngk irridum please can you help to solve this problem please and if you want i can send you a video for demonstrating sorry for my bad english i speack french more

  6. sunny says:

    hi chirs..
    finally we found the problem and that is rear cilinder carburator that is making the problem… the problem is after riding the bike distance 10km or 15mins drive, the bike get missing n shut off the engine because ECU send fuel quanitity little more expect its need to get, the front cilinder takes fuel correct quantity of fuel… technician tried twice a time n he got this problem.
    what u people suggest me to do?
    technician said me the ECU is faulty that y i get this problem…
    i dont want to spend the money on this bike anymore…so what u suggest me to do now
    is there any way to solve this problem to get reset the ECU and what is the process to do?

  7. Chris (Hyosung Rider) says:

    Hi Sunny, the V-Twin engine gets really hot, so don’t worry about that. The only way to solve this is to get a technician to look over it. If you don’t have a choice, you can unplug the cable, and when you ride long, please do stops. i.e. 100KM or 1 hour, whichever comes first.. take a break 10-15 minutes and continue riding it again. Good luck and sorry that I could not provide much assistance. Cheers

  8. sunny says:

    thanks chris for replying me…last time i used the engine oil 10W40 SAE API SJ; JASO MA-2(JASO T903:2006) after that im having this kind of problem…should i use 10W50 SAE JASO MA-2 (T903: 2011) API SL…here in italy temperature is normal..not so hot…but i think i should change the oil to see the result..
    i unplugged temperature sensor cable that is us located on front cylinder left side…also u can see on this page…what u suggest me?


    • Chris (Hyosung Rider) says:

      Hi Sunny, I don’t think the issue is with your Engine oil. The JASO greade is fine. See more info here if you want to choose a proper one.


      Hyosung V-Twin is always Hot, I can only think off your Engine Temperature Sensor is defective. Try replacing and see if that fix it? Let me know how you get on.

      • sunny says:

        hi Chris thanks for reply…i ll try to replace the sensore…hope i ll not get again this problem…

      • sunny says:

        hi chirs…i changed the sensor and also try to reset disconnecting the wires of battery…but im stil having the problem..i try to check the engine temperature with gauge and manual thermomter but temperautre go around 70 80 90 n also 95 C°… with the 95 C° temperature i try to check with multimeter using option ohm 20k and its show me 0.50 ..i dont know how i can solve this problem..if i unpulg the cabel that is located on sensore… bike dont make problem…but remain hot…can u tell me what to do now? and how much maximum engine temperature increase ? here in italy temperature maximum go 20 C°
        here i dont get the dealer of hyosung anymore..
        thanks i ll wait for replyyy

      • Chris (Hyosung Rider) says:

        Hi Sunny, I’ve already replied to your comment above.

  9. sunny says:

    hi every 1.i have hyosun gt250r 2008..i have in my bike engine temperature problem…when i start cold easily to start and i ride…but after 15 to 20km distance its get hot,touching the engine its look to hot…n then start missing the engine n shut off…need to keep off the bike for some mins to restart…but if i pull off the cable of engine temperature sensor…its start again n go long…also on the lcd disply never show me the temperature level…any 1 can tell me how i can solve this problm…how much goo maximum engine temperature in degrees?

    • Chris (Administrator) says:

      Hi Sunny, Thanks for dropping by and sorry you’re having problems. There is no temperature sensor for a 250CC GTR. I’ve ride my GT250R for hours before and never had problems with the temperature. I’m not sure which cable you exactly unplugged? I would suggest that you remove your seats and check the cable connected and ensure the sockets are intact especially on the ECU part. If you’re still having problems, try removing the batter cables whilst your engine is off, plugged it back in and ride and see if you’re still having problems. Good luck Sunny.

  10. Muhammad Fahmi says:

    hye bro,
    wanna ask your opinion regarding my problem,
    my bike didn’t have cold starting issue, but after i ride it, the engine will turn off automatically, and starting the bike back while engine is hot is almost quite impossible, if the engine started, it idles OK, but gradually decrease RPM and shuts off.

    what might be the possible source of error for this problem?

    • Chris (Administrator) says:

      Hi Fahmi,

      Sorry for the late reply. First of all, you will need to check the sockets and see if’s loose. Just remove the rider seats, check the ECU cables, relays etc. If that didn’t work, remove your battery’s cables and plug it back in after few minutes to do a soft reset. Failing that, Please bring it to local Hyosung or Naza centres to check via diagnostic tool and see if there is any error code. If you’re on a 650, it could be due to your temperature sensor. Give it a try and let me know how you get on by replying to this thread. Thanks and good luck.

  11. nitesh dwa says:

    where to get the hyosung diagnostic tool to buy online????

    • Chris (Administrator) says:

      Hi Nitesh,

      Unfortunately, Hyosung don’t sell this diagnostic tool online. This tool image was taken at Hyosung Service Centre.

  12. Wira Hazwan Rosli says:

    good job for highlighting this matter via blog…

  13. FROZ says:

    Well done bro..im getting my bike soon enough..hope i dont have all these problem.. for ur TBR exhaust Silver Series , is there any chances for me to get some sound of it? hehe im been waiting for that..

    • Chris (Administrator) says:

      Hi Froz,

      My apology for being late in responding to your request. I’ll upload it tomorrow. Please do visit my blog again. Thanks

    • Chris (Administrator) says:

      Hi Froz,

      The Video has been uploaded at my site. Please check it out. Cheers

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