♠️ M77
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If you get any issues, reply here and keep us posted. We do have those Acorn Nuts and Needle Jets (NJ) at the shop pages should you need them
I must say to caution with them little nuts , they don’t take much to get snapped , i’ve been there myself!
Hey,
Do you plan to fit them yourself or are you getting a helping hand for it all or was the mechanic asking?
Sorry for slow reply today
I suppose I could make up some draft tutorial ? – If you see the shop page i have asked customers to email me pics of their bikes before, after and during instal, just to prove how much of a “swap & go” business it really is, assuming they have worked on bikes before and knew the process. Most owners fit the kits themselves , with the odd owner or 2 asking me directly for assisstance on a small thing regarding a sprocket orientation etc. (which way it faces etc)
Welcome Marcus , its really good to have you on the forum , i can see more owners are growing on the forum that own the newer version of the GV125-S EFi
As last year, there wasn’t that many on road. I like the look of them but i do have my heart set on the eventual GV300SA , that’s the one i want 🙂
You will enjoy the GV125-S EFi for sure, plenty of support here if you need us! Although the EFI 125 is Hyosung’s 1st ever EFi Injected 125cc , they have been doing carb bikes for 125cc until 2019 ish and EFI 250/650 since 2008 , so other members will still chime in for whatever crops up.
Though, if you bought it new, you should be okay under a good care of your dealer. I say “good care” as some dealers/garages around the UK won’t touch Hyosungs which is silly so this is just a heads up! keep your warranty papers intact for servicing incase sinnis needs to send anything as they are the main importers of the bike (Real Hyosung UK through them as proxy)
Enjoy the summer !
Let us know the results of the compression test results (after the engine is hot, and crank bike full throttle with both plugs out) but tell the mechanic also cause sometimes they leave one plug inside causing bike to fire, the spark plugs must be physically out of the engine not just disconnected from the HT casps.
Just adding to what Tom said above ^ , go with what he says , even clearances pay dividents (valves too loose or too tight gets worse when bike is hot) thus , alas , the speed woes happen as valve head isn’t being 100% efficient.
If we can deal with the engine from top to bottom , before we can focus on any parts outside of the engine (whatever is under the frame responsible for keeping the bike going)
Clutch may be next , have macro meters and vernier calipers ready to measure the clutch , HP losses can happen on heat fatigued old springs and worn glazed up clutch plates , hence Korea says in their service books clutch should either be “looked at” or “changed” around every 4/5k due nature of the heavy bike with 2 hungry pistons , it can tax the clutch a bit.
keep us posted!
I don’t suppose you know of anywhere I can grab a service manual for the GV125S-EFI?
It will usually be supplied with the bike by Sinnis (the exclusive importer of Hyosung GV125 now/GV300S)
However, they will provide the “very least” an owners booklet and the service manual stays with the garage (whoever the garage is responsible for fixing your bike as per warranty schedules) ,
Being a brand new bike, i don’t expect drama already as long as its looked after , but ofcouse shout in this website if you’re stuck with something!
It looks correct, i can’t see how that will stop the bike running to be fair.
It sounds something else has gone off during the assembly / disassembly of the bike.
Also idle-adjuster is under the coils or it is near the front carb if korea put a short one.
I can see fuel in the filter, it is flowing. So that leaves out the tap & pump.
However, check vacuum leaks with a carb cleaner by spraying the intake pipes and check air pipes for any splits or kinks or bends
Also Hyosungs don’t like E10 , the carb 125s will usually make sure to punish the owner eventually when it keeps using e10. So if you have e10 , get rid of it and be ready to clean the carbs by only ULTRASONIC or AIR COMPRESSOR —- (Rattle cans won’t do the job, they aint agressive enough)
Firstly, welcome sir 🙂
This may go over your head but please trust me, can you do the following below first
- Let it get hot for 10mins. Then do a compression test.
Tell us what PSI each cylinder is , on full throttle. both plugs out. - Can you allow the bike to get overnight ice cold (required) then wake up , do a clearance check with a feeler gauge by taking valve covers off.
Tell us what each valve says,
eg. Exhaust Rear (sprocket side) = 0.26mm
eg. Exhaust Rear (cam chain side) = o.28mm
eg. Intake Rear (each side) = 0.13mm
Repeat
This
For the front engine.I will upload more manuals on the site when i get time. In meantime, checkout manuals lib site for “GT125 Service Manual” and follow instructions on how to test compression or clearance or let a garage do it real quick and get proof on paper. Don’t trust their lips.
- Also,
While at it, check your clutch plates with a VENIER CALIPER and measure thickness of each plate.
Also check how long the spring is (standing) , don’t compress a clutch spring. Eg. springs x2 35mm and other springs 32mm long etc..
What i said above, is critical to hit the 80 mark, otherwise the bike won’t do it no matter how tuned it is. So to save you money buying random things. Lets make sure the engine itself is healthy with the above checked.
Please report back and let us know how you get on!
Hello Stuart, can you please show us your fuel filter so i can see it is fitted in the right way
(they flow properly in one direction)Also it helps us see how you set up the pipes too.
Hi Guys, I have tested the stator and it works well. Also ignition coils and sparkplugcaps are ok, as tested with a multimeter. The Regulator and the CDI seem to be faulty. The reg is already on shipping, thanks again Marcel. Can I replace my CDI with any DC CDI from Amazon? Or can/would anyone recommend an explicit one for replacement??
Sorry for delay.
It should be only a “GV125” cdi specifically for yours. Because some Hyosung GV CDI’s have 3 plugs and some have 2 plugs.So i will assume your GV has 2 plugs under it. Replace CDI with the same one with 2 plugs for HYOSUNG GV125 only.
Other cdis from any bike or random ones may not work or will damage parts sometimes.
However, do test your CDI with ohms meter if you can , if you can try manualslib website for GV125 Service Manual page for your bike, it will show you how t test cdi.
(((I will upload more manuals on this hyoriders site when i get more time)))
Because the only way the bike gets power to the dash is via:
- Fuse/Relay box = as per simon
- Ignition Barrel (even its wires) =
HOWEVER, if the mechanism inside the “key barrel” acts intermittent, it will translate to power cuts instantly - The entire loom itself may need investigating because if there is a “shortt” anywhere inside the cables fraying or touching exposed inside the tape jacket
OR
The 1 cable somewhere is touching the frame, that will instantly turn the bike off and possibly blow the fuse too
However, if the “rear” and “front” lights stay on , and the dash stays “off”, then investigate the dash area and its mini loom that tries to join the main skeleton harness. Just a little heads up.
Hey welcome!
I hope you share pics of the bike when you get it on the forum, and wish you the best life with it 🙂I’d usually stay away from places like aliexpress for hyosung things as the general consensus on the whole internet can attest that fitting china stuff on hyosungs usually means buying twice or problems later of some sort. so i’m not sure to advise further here sadly.
However, because GV125-EFI is an entirely different animal, it shares zero parts from its older generations , so much so that even all the part numbers i know in trade all have “1234567KGZ0000” as opposed to older hyosungs having “12345HG0000”, cross referencing will not be easy until you yourself see the gear switch in the flesh aswell as seeing how the shift linkage works.
Hell, ive seen a chinese item with 2 magnets that basically signal each other on every gear shift until the rider stops , and the gear indicator is ofcourse its own LCD.
When I press the starter button the engine starts to turn over and then stops with a clank noise. I changed the starter and battery. Still happens but it’s intermittent.
Are you certain there is no missing teeth on the big sprocket that is behind the flywheel drum ?
It will start to turn over and then come to a crashing stop in the first second or so of kranking it. It almost sounds like it’s hitting something as it’s trying to turn over. The only other observation is that when it’s having this problem the wires to and from the solenoid get very hot. I also checked the starter clutch and it is solid in one direction and spins freely in the other direction. Any ideas would be welcome. Thank you!
I am very suspicious of the “Sprag Clutch” that sits behind the flywheel drum, if in doubt, i’d replace it. Sounds similar to a bike i’ve worked on a while , it was a GV250 that was notorius for having missing teeth of the sprocket or sprag clutch got too old / annoyed causing the starting system (electrics) to get drained fast
– Alas starter motor dies sooner from stress cranking
– Solenoid, burns out.If it starts on pushing and dropping to 2nd gear.
This issue now points to funny behavior that concerns these parts mainly
- Starter Motor Unit
- Check the wires, if in doubt, use thicker gauge wires.
- Sprag Clutch
- Flywheel sprocket
- Hopefully flywheel “Half-MOON” shape key is in still inside the crank shaft where the drum slides in to, so it clocks the “drum” only from free spinning
(I would assume so, otherwise if a drum free spins, it will certainly undo the center flywheel nut)
Red Paint is “Hyuindai Electric Red”
You’re welcome 😉
50 will will have a slightly higher heat tolerance before the oil starts to break down. The “10w” in the bottle must stay that way forever as the hardest life the engine gets is also when you start it , the oil must race to the crank and lubricate so the parts don’t degrade too fast (metal to metal grinding)
15w/20w is too thick for our climate. However, 40/50 on the bottle (without “W”) is safe for all year use.
Hi Marcel, the revs rpm reading, I heard it could be an empty battery.
RPM Revs reading comes from dashboard wire that is colour “Yellow/Black” (usually) and it works by signal from these devices below (so check them)
– Stator
– CDI
– Harness (Mystery sensors inside hardness/ aka. Mystery diodes)
– Ignition CoilsHave a look at this topic below for some ideas on electrical troubleshooting and how to test parts with a meter
It is a GT250 yes but still carby, and they sometimes use same coils , caps, & regulator as GV125
Only stator / harness / switches and some other electrical parts are only for GV125 but either way it should give you some idea.
No it will love highway rides more than little city rides because there is not enough speed & air in the city to keep it cool due to speed limits. But the city sucks because too much time is spend in traffic and idling.
Motorways are fine.
For even better benefit , get a Hyosung 250 Cooler (GT250 or GV250) and the rear cylinder will thank you. The GTR gets a little less air at the rear engine to cool it because it has plastics hiding it (for aerodynamics and sporty look). The Naked GT do not have the problem.
Also Ester oil helps, use good quality oil. In my own opionion (because everyone on the internet always has a “favourite” brand) but i can assure you Hyosungs love Motul or Silkolene oil (Motul 7100 or 300v //// Silkolene Comp 4 or Pro 4)
I use 10w40 in winter and i use 10w50 all summer. I do not buy 5w because its too thin, and avoid 15w/20w because it is too thick. Our European countries do not need 15w/20w even the UK (even if its out of EU, it is still mostly a cold climate)
Hi all Still having starter issues. Is there a way to adjust the timing on the GV65O 2007 and would that help the starting problem? Thanks
Can you explain more of the starting issues?
Also secondly, do you see good sparks from the plugs and fuel is getting to the cylinders?
Motul 7100
Motul 300v
Silkolene Pro 4
Silkolene Comp 4These 4 are always what i love to use and wouldn’t even touch the likes of castrol or some other hyped up brand. Silkolene & Motul Ester oils do exactly as they say and i always seem to get a better mileage out of and gearbox is always smoother to shift thru , like butter.
But other brands work , however after 500 miles or something they quickly turn black and the gearbox can feel crunchy sometimes.
Just my 2 pence 🙂
Hello Marcel, since yesterday the speedo does not work anymore. which part of the motorcycle is responsible for the speedo?
Do you mean MPH reading or revs (rpm ?) or fuel gauge reading ?
Hi Marcel, I have already done valve clearance —> everything in tolerance Clutch —> Already replaced
—> air filter new —> manifold orings new Regarding the cap, just any cap from a mechanic near by, not even new I think. There were cracks in the previous cap. How long is the shipping of the coils from the store? Caps would be good too in that case.. What do you think about the CDI?? Not possible that it causes the problem?An NGK cap would be better, some caps have too much resistance. (20 ooo ohms etc, not good for carby hyosung) , Hyosung oem caps are under 10K usually, NGKS would be less, like the ones i keep on the store.
Speaking of store, you will need to send me an email with your address so i can see how long it takes to arrive for the coils.
CDI can be faulty yes but usually when it is dead, it stops sparking. You may download the GV125 service manual and check resistance of the cdi terminals with a pocket meter.
- Let it get hot for 10mins. Then do a compression test.
