Hyosung Motorcycles - Recent Questions, Troubleshooting & Support


Hi, Feng and the usual suspects are:
1. Extremely lean fuel mixture.
2. Dirt, rust, water, or ethanol sludge in the fuel system.
3. Sticky throttle cables.
4. Multiple carburetors not in synchronization.
5. TPS sensor out of adjustment or faulty.
6. Wrong spark plugs for the type of service.
7. Throttle bodies not in synchronization (FI)
8. Faulty O2 sensor.
9. Clogged, stuck, or faulty IAC valve.
10. Aftermarket components are not compatible with ECM.
For more information about your issue and valuable "FREE" downloads that you will need for viewing or printing please click on the blue links below. Good luck and have a wonderful day.
http://korider.com/index.php?topic=26692.0
https://www.scooterdynasty.com/250cchyosunggv250aquilacruiser.aspx
Hyosung Aquila 250 Service Manual
https://alpha-sports.com/hyosung_parts.htm
https://www.manualslib.com/manual/406874/Hyosung-Gv250.html#product-Aquila%20250

2014 Hyosung GV... | Answered Yesterday


Hi, Anonymous before testing any electrical component in the Starting Circuit it is "IMPERATIVE" that you have a fully charged battery of 12.5 volts or more and be able to pass a proper "LOAD" test if necessary, you may have a preliminary reading of 12.5 volts or more but little or zero amperage, the battery is faulty and must be replaced. AGM type batteries fall into this scenario more so than lead-acid batteries.
1. Ignition Switch not in the "ON" position.
2. Engine Run Switch in the "OFF" position.
3. Engine Run Switch is "FAULTY" or corroded.
4. Check the battery terminals for damage or corrosion check the battery cables at "BOTH" ends for loose, corroded, or broken connectors, "INSIDE" and outside the cable harness, perform connector wiggle test and check cables with an ohmmeter.
5. Bank angle sensor needs a reset or is faulty.
6. FOB battery low or dead.
7. Faulty ignition switch.
8. Faulty starter button.
9. Faulty kickstand, clutch, neutral safety switch.
10. Security alarm needs a reset.
11. Starter relay, solenoid, starter motor or circuit wiring faulty.
12. Starter armature or field coils have failed.
13. Main fuse or circuit breaker may be blown or faulty.
14. Faulty ignition relay.
15. The electric starter is working but starter clutch has failed.
16. Check for engine trouble codes.
For more information about your issue and valuable "FREE" downloads that you will need for viewing or printing please click on the blue links below. Good luck and have a wonderful day.
https://www.reddit.com/r/Fixxit/comments/5j64lc/hyosung_gv_250_motorcycle_wont_start_wont_crank
https://www.google.com/search?q=Will+not+turn+over+Hyosung+GV250+Aquila&tbm=isch&source=univ&sa=X&ved=2ahUKEwiivJDh-vLiAhUvzlkKHdVdA6AQsAR6BAgDEAE&biw=1440&bih=757
Hyosung Aquila 250 Service Manual
https://alpha-sports.com/hyosung_parts.htm
https://www.manualslib.com/manual/406874/Hyosung-Gv250.html#product-Aquila%20250

2002 Hyosung GV... | Answered Yesterday


Hi, Anonymous and the usual suspects are:
1. Low coolant level.
2. Restricted radiator air flow.
3. Faulty thermostat.
4. Coolant pump or fans inoperative.
5. Vent hose crimped.
6. The air in the coolant and needs bleeding.
7. Engine idling too long or bike moving too slow.
8. Coolant too old needs to be replaced.
9. Faulty temperature sensor, wiring or connector.
10. Radiator veins clogged or corroded needs repair
11. Cooling system leak.
12. Ignition timing retarded.
13. Spark plug heat range too high.
For more information about your issue and valuable "FREE" downloads that you will need for viewing or printing please click on the blue links below. Good luck and have a wonderful day.
http://korider.com/index.php?topic=22214.0
https://www.ebay.co.uk/b/Hyosung-Motorcycle-Engine-Cooling-Parts/177962/bn_79386626
Hyosung Aquila 250 Service Manual
https://alpha-sports.com/hyosung_parts.htm

2003 Hyosung GV... | Answered Yesterday


Hi, Motorbike01 for this scenario you will need your service manual, parts fiche, and owners manual if you can't find the best tool you ever bought for your Hyosung, despair not, for a mere zero $0 you can download another one.
For more information about your issue and valuable "FREE" downloads that you will need for viewing or printing please click on the blue links below. Good luck and have a wonderful day.
https://www.google.com/search?q=Battery+location+2003+Hyosung+GV+125+Aquila&tbm=isch&source=univ&sa=X&ved=2ahUKEwjDi5Xm9_LiAhUM0FkKHTp1D1kQsAR6BAgEEAE&biw=1440&bih=757
https://www.youtube.com/watch?v=tzmJYuzndAE
http://www.banici.pl/bam/Tom/GV125/Instrukcje/GV125_SERVICE_MANUAL_EN.pdf
https://alpha-sports.com/hyosung_parts.htm
http://mybikemanuals.com/hyosung/hyosung-gv-owners-manuals

2003 Hyosung GV... | Answered Yesterday


Hi, Fourthquantu if you have changed your engine size, compression ratio, fuel delivery system, air filter size or flow rate, mufflers or exhaust system or a significant change in altitude your carburetors need re-tuning and if your fuel system (gas tank, filters, fuel valve, and carburetor) is contaminated with ethanol sludge, varnish, rust, dirt, water, etc. or your bike has been sitting for months or years without running these components must be "PROPERLY" cleaned and reassembled "CORRECTLY" before any adjustments can be made. Tuning your carburetor is fairly simple once you understand the basic principals. Your engine is a simple airbox sucking air in and blowing it out, it is finely tuned at the factory for maximum performance once you upset that delicate balance by changing air filters, camshafts or exhaust systems your performance may go down the and the engine may run poorly, you need to compensate the air-fuel mixture in the carburetor in order for the engine to run smoothly and at peak performance. If you are running multi carburetors you need to sync them first and make sure your air cleaner element is clean and dry for paper elements or lightly oiled for foam and meshed elements and properly installed. Here is how and where you compensate trouble: "TIP" if your engine "BOGS" you're not getting enough fuel.
1. Close to 1/8 throttle is managed by the air screw and pilot/slow jet.
2. 1/8 to 1/4 throttle is managed by the air-screw, pilot/slow jet, and throttle slide.
3. 1/4 to 1/2 throttle is managed by the throttle slide and jet needle.
4. 1/2 to 3/4 throttle is managed by the jet needle, needle jet, main jet, and air jet.
5. 3/4 to wide open throttle is managed by the main jet and air jet.
6. A wide open throttle is managed by the main jet.
If you are running lean, spark plug electrode color is white, the engine runs hot and feels like it is starving for fuel you need to go up on the jet size or move the c-clip down one notch. If you are running rich, spark plug color is black or dark grey, the engine runs cool, and bogs down when accelerating you need to go down on jet size or move the c-clip up one notch. When your carburetor is properly tuned for maximum performance your spark plug electrode will be a light tan color like coffee with cream. If you prefer fuel economy over performance you can go down on main jet sizes until a satisfactory level of lower performance is acceptable versus MPH, your spark plug color will be whiter and your engine will run warmer. These tuning adjustments will only make improvements if your intake and exhaust system have no air leaks or sealing issues and the entire electrical system is in proper working order and you have no mechanical issues.
For more information about your issue and valuable "FREE" downloads that you will need for viewing and printing please click on the blue links below. Good luck and have a wonderful day.
https://hyoriders.club/forums/topic/tutorial-hyosung-gv-gt-125-250-how-to-swap-carburetor-main-jets
hyosung gv250 carb balance with 2 bottle manometer
http://www.banici.pl/bam/Tom/GV125/Instrukcje/GV125_SERVICE_MANUAL_EN.pdf
https://alpha-sports.com/hyosung_parts.htm
https://www.manualslib.com/manual/860797/Hyosung-Gv250-Ei.html#product-GV125%20-%20CATALOGUE

2001 Hyosung GV... | Answered Yesterday


Hi, David for this scenario you will need your service manual, parts fiche, and owners manual if you can't find the best tool you ever bought for your Hyosung, despair not, for a mere zero $0 you can download another one.
For more information about your issue and valuable "FREE" downloads that you will need for viewing or printing please click on the blue links below. Good luck and have a wonderful day.
https://www.google.com/search?q=Wiring+diagram+2003+Hyosung+GV+125+Aquila&tbm=isch&source=univ&sa=X&ved=2ahUKEwiQjtWH4vLiAhVEzlkKHekXBCIQsAR6BAgEEAE&biw=1440&bih=757
https://www.manualslib.com/manual/865104/Hyosung-Aquila-250.html?page=202
HYOSUNG GV250 User Manual

2003 Hyosung GV... | Answered Yesterday


Hi, Wangiboy derestrict is a negative term rider's use to express their wish to improve performance on their bike or scooter. Depending on the country and motor vehicles laws some bikes and scooters are designed to conform with said laws and their performance is slightly lower than other countries. All vehicles in the world are designed to perform at 75-80% of their maximum potential, this ensures the longevity of the engine. Derestricting or improving performance is always possible on any vehicle but the tradeoff of engine longevity numbers go down, how much depends on the number and type of performance upgrades. Your local dealership or reputable independent shop are best equipped to provide you with technical data and willingness to comply with your needs.
For more information about your issue and valuable "FREE" downloads that you will need for viewing or printing please click on the blue links below. Good luck and have a wonderful day.
How to derestrict an EFI Hyosung GT650 LAMS model
https://netrider.net.au/threads/derestricting-a-650-hyosung-as-a-track-bike.250804
HYOSUNG GT 650 Service Manual
https://alpha-sports.com/hyosung_parts.htm
HYOSUNG GT 650 Manual

2005 Hyosung GT... | Answered Yesterday


Hi, Kat_282001 the vast majority of service, parts fiche, and owners manuals on the internet are "FREE" to download and all service manuals contain wiring diagrams in the back pages. The rest usually charge a modest fee of $15 and there is a handful of obscure, rare, obsolete, and very old models that are no longer or never were available and some were never printed in English. The Indian and Philippine markets are usually in E-book format only, for these rare occasions I shall look on eBay and find the cheapest one available. Most of the manuals will cover your exact make, model, and year otherwise one will be provided that comes as close as possible to your bike and will have most of the same info that an exact manual would have. If there is no $ sign after the manual link it is free to download.
To download your manual for viewing or printing please click on the blue links below. Good luck and have a wonderful day.
HYOSUNG GT 650 Service Manual
https://alpha-sports.com/hyosung_parts.htm
HYOSUNG GT 650 Manual
https://bikez.com/motorcycles/hyosung_gt650s_sport-comet_650_s_2007.php
HYOSUNG GT 650 Manual

2006 Hyosung GT... | Answered Yesterday


Hi, Anonymous and the usual suspects are:
1. Low coolant level.
2. Restricted radiator air flow.
3. Faulty thermostat.
4. Coolant pump or fans inoperative.
5. Vent hose crimped.
6. The air in the coolant and needs bleeding.
7. Engine idling too long or bike moving too slow.
8. Coolant too old needs to be replaced.
9. Faulty temperature sensor, wiring or connector.
10. Radiator veins clogged or corroded needs repair
11. Cooling system leak.
12. Ignition timing retarded.
13. Spark plug heat range too high.
For more information about your issue and valuable "FREE" downloads that you will need for viewing or printing please click on the blue links below. Good luck and have a wonderful day.
https://www.reddit.com/r/Fixxit/comments/apcpwk/2010_hyosung_gt650r_overheating
https://www.youtube.com/watch?v=MrBI1hRTgx4
HYOSUNG GT 650 Service Manual
https://alpha-sports.com/hyosung_parts.htm
HYOSUNG GT 650 Manual

2006 Hyosung GT... | Answered Yesterday


Hi, Anonymous derestrict is a negative term rider's use to express their wish to improve performance on their bike or scooter. Depending on the country and motor vehicles laws some bikes and scooters are designed to conform with said laws and their performance is slightly lower than other countries. All vehicles in the world are designed to perform at 75-80% of their maximum potential, this ensures the longevity of the engine. Derestricting or improving performance is always possible on any vehicle but the tradeoff of engine longevity numbers go down, how much depends on the number and type of performance upgrades. Your local dealership or reputable independent shop are best equipped to provide you with technical data and willingness to comply with your needs.
For more information about your issue and valuable "FREE" downloads that you will need for viewing or printing please click on the blue links below. Good luck and have a wonderful day.
How to derestrict an EFI Hyosung GT650 LAMS model
https://netrider.net.au/threads/derestricting-a-650-hyosung-as-a-track-bike.250804
HYOSUNG GT 650 Service Manual
https://alpha-sports.com/hyosung_parts.htm
HYOSUNG GT 650 Manual

2006 Hyosung GT... | Answered Yesterday


Hi, Benadesgaao your instrument gauges and lights can alert you to most electrical and engine issues they can not warn you about failed engine gaskets or seals so your engine has to resort to old fashion alert methods of colored "SMOKE SIGNALS" here is a breakdown of their meaning:
1. COLORLESS OR SLIGHTLY BLUE SMOKE on start-up means your air/fuel mixture is the right composition and everything is well burnt in your combustion chamber.
2. BLUE SMOKE on startup is usually caused by failed valve seals dripping oil into the combustion chamber when the engine is not running.
3. YELLOW OR BROWNISH SMOKE at start-up means your air/fuel mixture is too lean. Too lean means that there is low fuel but high air mixture in your combustion chamber.
4. WHITE SMOKE on startup may be caused by a blown head gasket allowing coolant to enter the combustion chamber and may start dripping out of the exhaust pipes or mufflers. Smoke while riding is usually caused by worn out or damaged valves, seals, guides, pistons, rings, or cylinder walls.
5. BLACK SMOKE on startup is usually caused by too much fuel in the combustion chamber this can be due to air/fuel mixture adjustment too rich, accelerator pump improperly adjusted, faulty choke or not in the off position, air filter dirty and clogged, faulty carburetor float needle and seat, pilot jet too large, fuel injectors leaking, smoke while riding is usually caused by the main jet being too large or a damaged carburetor.
It should be noted that aggressive or abnormal throttle operation will cause these conditions to manifest themselves exponentially.
For more information about your issue and valuable "FREE" downloads that you will need for viewing or printing please click on the links below. Good luck and have a nice day.
http://korider.com/index.php?topic=22928.0
https://www.youtube.com/watch?v=8YfEIP6eRzs
HYOSUNG GT 650 Service Manual
https://alpha-sports.com/hyosung_parts.htm
HYOSUNG GT 650 Manual

2006 Hyosung GT... | Answered Yesterday


Hi, Beartom before testing any electrical component in the Charging System it is "IMPERATIVE" that you have a fully charged battery of 12.5 volts or more and be able to pass a proper "LOAD" test if necessary, you may have a preliminary reading of 12.5 volts or more but little or zero amperage, the battery is faulty and must be replaced. AGM type batteries fall into this scenario more so than lead-acid batteries.
1. Check battery terminals for damage or corrosion, check the battery cables at "BOTH" ends for loose, corroded, or broken connectors, "INSIDE" and outside the cable harness, perform connector wiggle test and check cables with an ohmmeter if necessary.
2. To check the regulator unplug it from the stator. Take a test light and clip it to the negative terminal of the battery and then touch first one pin and then the other on the plug that goes to the regulator. If you get even the slightest amount of light from the test light the regulator is toast.
To do this with a meter: black lead to battery ground, red lead to each pin on the plug, start with the voltage scale higher than 12vdc and move voltage scale down in steps for each pin. Any voltage is a bad regulator.
3. On the other part of the disconnected regulator plug. Set the multimeter for Ohms x1 scale and measure for resistance across the pins of the stator. You should read something around 0.1 to 0.2 ohms for a 32 amp system.
4. Then check for continuity between each pin on the plug and frame/engine ground. The meter needle should not move (infinite resistance)(digitals will show infinite resistance) if the meter needle does move (indicating continuity)(digitals will show some resistance), recheck very carefully. If the meter still shows continuity to ground the stator is shorted (bad).
5. Set the meter to read A/C volts higher than 30 volts (the scale setting for voltage should always be higher than the highest voltage you expect or you may fry the meter). Start the bike, and measure from one pin to the other on the plug (DO NOT cross the multimeter probes! - touch them to each other). You should read roughly 16-20 vac per 1,000 rpm.
6. If the battery was good under load test, if the stator is NOT shorted to ground, and the stator is putting out A/C voltage, then the regulator is bad (most likely even if passed step 2)
For more information about your question and valuable "FREE" downloads that you will need for viewing or printing please click on the blue links below. Good luck and have a wonderful day.
Hyosung Gt650R battery not staying charged
http://korider.com/index.php?topic=14684.40
HYOSUNG GT 650 Service Manual
https://alpha-sports.com/hyosung_parts.htm
HYOSUNG GT 650 Manual

2010 Hyosung... | Answered Yesterday


Hi, John for this scenario you will need your service manual, parts fiche, and owners manual if you can't find the best tool you ever bought for your Hyosung, despair not, for a mere zero $0 you can download another one.
For more information about your issue and valuable "FREE" downloads that you will need for viewing or printing please click on the blue links below. Good luck and have a wonderful day.
https://www.google.com/search?sa=X&q=Fuel+and+vacuum+line+routing+2005+Hyosung+GT650R&tbm=isch&source=univ&ved=2ahUKEwjauaOm2PLiAhWpxFkKHSRSD-IQsAR6BAgBEAE&biw=1440&bih=757
Vacuum and fuel line routing
HYOSUNG GT 650 Service Manual
https://alpha-sports.com/hyosung_parts.htm
HYOSUNG GT 650 Manual

2005 Hyosung GT... | Answered Yesterday


Hi, Jd145505 and the usual suspects are:
1. Contaminated or faulty speed sensor.
2. Faulty turn signal module.
3. Corroded, broken or loose connector pins/sockets in the wire harness between the speedometer and the ECM or TSSM and the sensor.
4. The speedometer unit has failed.
5. Speedometer instrument fuse has blown.
For more information about your issue and valuable "FREE" downloads that you will need for viewing or printing please click on the blue links below. Good luck and have a wonderful day.
http://korider.com/index.php?topic=20334.0
How to Fix Motorcycle Speedometer SpeedoDRD
HYOSUNG GT 650 Service Manual
https://alpha-sports.com/hyosung_parts.htm
HYOSUNG GT 650 Manual

2005 Hyosung GT... | Answered Yesterday


Hi, Redtex110 and the usual suspects are:
1. Clutch not properly adjusted.
2. Clutch plates rusted together.
3. The hydraulic clutch needs bleeding.
4. Faulty clutch slave cylinder.
5. Faulty clutch ramp mechanism.
6. Broken clutch rod
7. Clutch pack loose on the main shaft.
For more information about your issue and valuable "FREE" downloads that you will need for viewing or printing please click on the blue links below. Good luck and have a wonderful day.
http://korider.com/index.php?topic=16876.0
https://www.kiwibiker.co.nz/forums/showthread.php/109741-Hyosung-GT250R-clutch-gearbox-issues
HYOSUNG GT 250 Service Manual
https://alpha-sports.com/hyosung_parts.htm
https://www.manualslib.com/manual/406858/Hyosung-Gt-125-R.html#product-Aquila%20GT250%20R%20Ej

2016 Hyosung GT... | Answered Yesterday


Hi, Michael10100 for this scenario you will need your service manual, parts fiche, and owners manual if you can't find the best tool you ever bought for your Hyosung, despair not, for a mere zero $0 you can download another one.
For more information about your issue and valuable "FREE" downloads that you will need for viewing or printing please click on the blue links below. Good luck and have a wonderful day.
https://www.manualslib.com/manual/406860/Hyosung-Gt-650-Efi.html?page=45
https://www.youtube.com/watch?v=LSYAe22poZI
HYOSUNG GT 650 Service Manual
https://alpha-sports.com/hyosung_parts.htm
HYOSUNG GT 650 Manual

2010 Hyosung... | Answered Yesterday


Hi, John021 for this scenario you will need your service manual, parts fiche, and owners manual if you can't find the best tool you ever bought for your Hyosung, despair not, for a mere zero $0 you can download another one.
For more information about your issue and valuable "FREE" downloads that you will need for viewing or printing please click on the blue links below. Good luck and have a wonderful day.
How to Bypass the kickstand safety switch on motorcycle
https://www.dailymotion.com/video/xbp93a
HYOSUNG GT 650 Service Manual
https://alpha-sports.com/hyosung_parts.htm
HYOSUNG GT 650 Manual

2006 Hyosung GT... | Answered Yesterday

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