♠️ M77
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If you unscrew the HT wires away from the coil so it is by itself (Yes the actual HT wire should be unscrewed so the cone has no wire attached to it)
Tell us again the primary and secondary resistance of each coil
Eg. Coil Front
– 0.6 Ohm (less than a single ohm)
– 12,000 ohms (12.K)We can match those with the service manual if its in spec or not. It helps to get a picture of the coils on the bike, Hyosung used variations of coils until they settled with a Delphi Shotgun coil after 2013+.
Hi , this sounds stupid, is it possible that we have no vacuum due to air leak from the intake orings ? Like below:
Intake Pipe O-RING (Inlet Boot Seals) x2 – GV125 GT125 RX125 GV250 GT250 Hyosung
So in essense, the GV125 is quite sensetive to how much vacuum loss happens and makes it very hard to start (and it prefers the airbox systems to all stay joined up down to the air filter itself) (Hopefully it is not running on pod filters as they hate it)
If you’re totally sure the intake system has zero leaks , look at the carbs again and blow the Pilot Jets one more time. The hole for the jets don’t take much to clog them.
Also see the “Permanent Jet” that is next to the pilots ? It is the tallest & skinny jet with the smallest hole, can’t be removed from bike = This controls starting the bike, you want to blow that hole as hard as you can to free up any debris.
Then put everything together slowly , turn on FULL choke, crank the bike while twisting throttle up & down (every quickly!) for max 5 seconds (as not to overheat the starter motor) = you should see fuel rushing down the filter and going to the carbs
It should start….
If not , crank the bike for a few seconds and switch off. Wait a whole 5 mins to cool the starter motor , crank again…. Stop ===> Open the “Drain Screws” and have a CUP under them.
See which bowl is getting more fuel than the other ===> eg. Front carb gets fuel OK, it drains out on the float bowl screw mini pipe but the rear does not drip any fuel out, this means rear carb is jammed or re-do the whole float system on both carbs.
Float height should be around 7.00mm to 7.5mm max (This is when the carb floats are resting on the carb float seats and they are facing the sky (carb is upside down)
Look at this topic and read float height information if it helps below:
Let us know how you get on or if you need clarification on anything I’ve said.
The frame is smaller and different than any previous generation hyosungs that before it. Also it is the “only” fuel injected 125cc they have and all its electronics are locked to the 125cc (they will respond to that specific engine only)
Also, the frame also has mounting points designed around that frame. The frame is a bit weaker than the older generations for sure, so unless you have someone next to you who can cut the frame & fit some other engine from another 125cc bike that uses fuel injection , then “reinforce” it extra hard so the frame doesnt snap or twist or flex (structual warning)
Other engines = All electronics must come from the donor bike, otherwise you will have more hell trying to figure out the electrics.
How much does your garage cost to replace the crank for you ? At least if they do it, you will ride after the job is done.
Fuel Pump could be #1 suspect and also its Relay. But the pump for that bike needs to maintain some good presure as the injectors could only spray as quick as they can based on ECU timings . The ECU won’t tell you if the pump is faulty (if its still running), it can only trigger it on or off.
It brings us to the injector being the next domino to fall. I’d try to clean the injector but be ready to replace it.
Ignition coil = Remove the HT Plug Cap (unscrew it, don’t pull it off) ==> Test only the ignition coil for PRIMARY & SECONDARY resistance. Tell us the values. Make sure the coil is cold.
HT Cap on its own = Measure the wire and the spark plug tip inside ==> Tell us if its 5,000 , 20,000 or 50,000 ohms.
(All OEM caps can sometimes be the reason there is sparking issues , but rarer on a GD as it’s not spoken about as much)I did a couple of tests though I’ll order one now Meanwhile the motorbike is stopped for now Do you know where I could find them?
I could not find one to order yet (out of stock from Hyosung Korea until they make more) , but fix your email please and message me. I will try to get an aftermarket caliper for you that could fit , you could try it.
Ride safe, lots of rain & wind coming this weekend!
Hey, I am sorry about that. Are you sure it is safe to ride like that ? I see a crack in the picture?
Brakes are important, I would not want you on A&E 🚑 if the caliper locks up at high speed or pads fly away, the little screw was to stop the pin from rattling out (It has happend to me before on my GT, but luckily the caliper had 2 pins, so i was able to ride slowly and order new stainless pins & new screws. I always made sure to check my calipers. This is a very bumpy country!)Welcome to the site! Post a picture of her 🙂
By all means , make a topic and tell us all about it, I am sure we will get it going smoothly again. If you have time , have a look at some older threads to see if some answers were there for your specific issue?
Get the spark plug out , when you can and show us the colours, but try again with a fresh CR8E plug only , check if the injectors work properly
You may possibly misfire due to poorly injector? (Something similar in this topic, but it was the injector in the end)
Voltage regulator seems to be working OK for now , so keep an eye on it. Idling at 13.8V is not bad , it’s good. 14.5V should be the max , if it spikes beyond 14.8V i would replace it as EFi ECU doesn’t last very well running too high due to delicate electronics inside. A carb bike will handle 15V but it won’t like it long term.
Long Bolt = It is a pin for the brake pad.
“Little Screw” = it is to stop the long bolt from falling out, it is required on all Hyosung machines.
Hyosung GV125-S from factory uses “Little Screw (grub Screw”) ==> Long Bolt (Caliper Pin) = Both of these 2 go inside the caliper.
Maybe yours is missing a “little screw” , that is why we send you stainless.
You will now need a long bolt “Caliper Pin” like the link i posted above ^ because the old parts show be thrown away after fighting to remove it (They will be worthless as i can see in first picture above ^ you will not use those parts again and upograde to stainless steel
Make sure to buy “COPPER GREASE” for pistons , screws , and the RED section of your brake pads, they will stop them getting stuck , next time you do maintenance
Hope this helps
a lot of cruisers in USA don’t have big displays and they are too basic (speed and mileage) , hell even the old Hyosung Gv650 2007 has no rev counter.
But because they are naked with carbs , it was easier to make a custom mount to the handlebars and fit a KOSO USA gauge on it , but the pain was working out the wires and allowing the bike to respond.
KOSO may even inaccurately read fuel levels (it says 4 bars , but you have 1 bar inside the tank, there is a risk of being stranded if too far from a petrol station) unless you know the “MPG” of the bike itself , ride like a granny , and if you go 100 miles , then put 100 miles worth of fuel in the tank. Another old school way not to always “trust” what the fuel level display says
Your 125R’s fuel level is optimistic at best but it tries its best to be accurate. Usually 1 bar on the 125R taking it easy with E5 fuel means you have about 10-15 miles to find fuel) before it starts flashing critical.
Other Hyosung riders will definitely find your topic (this one) as you research and find answers. You will tell us if it was worth it or not.
You have 1 more chance === Try a BIGGER Allen Bit and hammer it in. Then turn it loose. Also spray WD40 to loosen any old road rust
or use bigger TORX bit and hammer it in, so that it is stuck hard on the bolt, then you have 1 chance to loosen it. Then throw it away.
I really recommend stainless pin FIRST before doing that , because you don’t want to re-use that damaged pin again (they used bad steel).
Stainless Steel Brake Caliper Pin (x1) (Pad Retaining Bolt Axle) :: Hyosung GV125-S EFi
Isn’t the display already LCD? – The OEM display that’s fully LCD is Hyo’s newer 2020+ GV300S and Gv650s in Japan but they are not backwards compatible with carby bikes.
The “plastic surround” on your bike is molded to fit the current display you have and the bike’s electrics expect that Orange Backlit gauge to be there , otherwise 99% of all digital displays that are aftermarket WILL fail at some point if not much sooner as sold in china sweat shops.
If you can fork out big money for a dash that will last well, you could look at a KOSO USA gauges (beware of clones, so many clones!) and you have to learn to rewire everything with a fresh connector and wires (no point chopping up your old loom cables , as you will be lucky to find another one at this rate) so expect to have a 9-PIN connector and long sets of cables. Now your new dash should plug & play and remove if you need to restore the old dash.
The plastic surround will be cut around, so buy a new plastic surround and mold / cut your new dash in to it.
Speed Sensor on the left fork is calibrated to run on your OEM dash, aftermarket dashes probably come with magnets attached to fork leg and brake disc to “estimate” speed (but not always perfect!) , so have GPS as a backup as we have more cameras everywhere now lol.
I could be old fashioned to say i prefer how Hyosung did it = RPM tacho + LCD speed display with icons (high beam, neutral, etc) on their own too instead of being intergrated in to the LCD display.
If i ever know someone who has used a real Koso gauge on the 125R, i would ask them to make the tutorial on the forum
We seem to have spark but it still runs the same with the front leed off.
As mentioned before , you have to try my previous reply in regards to swapping things around to back cylinder , checking injectors
If you can, get the service manual in this forum and report back here with a multi meter when the bike is COLD:
– Stator values (It is the first thing to tell engine ECU when to spark)
– Ignition coil values (primary and secondary resistance)
– HT Cap values (on its own) (eg. 45K ohms)It can narrow things down taking away most of the guessing , either way you have a cold cylinder, something isn’t right unless you have a Heat Gun that can measure accurately what temperature the cylinder actually is eg. Rear Exhaust pipe = 150 degress celcius , Front Pipe = 44 deg. *C
We can then determine finally if you are fuel starved there or electrical misbehave (lethargic sparks at the front etc)
That’s a shame that they don’t make them anymore. How much are you looking at selling for/ could you send me a link when you do put it up? As I said I am currently without a Speedo and while I can use GPS, my problem is tracking miles
Send me an email for a sale quote now (GPS on WazeApp is a good backup!)
If the cylinder is cold = No sparks are happening , so check again that it is sparking,
Swap the coils & caps front and back , then the rear cylinder should be cold , and front hot
If it makes no difference swapping ignition parts = Then check the harness is actually sending signals on those lines otherwise you have a damaged circuit along the harness that’s leading to that coil
You also want to make sure for example front cylinder has a wire that is “BLACK with GREEN LINE” —> measure that line at the ECU end for breaks (dead signal / loss along the harness) or the meter will tell you the line is complete and there is no breaks.
You want to be sure the injectors are working ===> Start the bike as you would, if the cylinder is cold. Turn her off , then remove the spark plug of that cylinder, it should be very wet with fuel ? , if else swap injectors around. And see if the rear cylinder gets cold and front engine gets hot ?
Hey! 🙂
I will research more in to that product , as some one in the past tried to do something similar , he had bigger problems with his bobber later (engine later got damaged) but he was also abusing it (racing the engine too hard)
CR8E is the correct plug = It will hate CR9E a lot. No IX they hate it. Just keep it basic CR8E , if it won’t run on a factory CR8E plug, there is bigger issues likely compression problems and valves too tight.
Yes the stator & RR will make the ignition coils go funny at times
There is a guide on the forum called “Battery Test” , follow it and there is a picture inside on how to test the Stator , Coils , Caps and report the figures here.
Either way get the engine compression checked and clearances checked it will save a lot of headache later
Upgrading fuel parts just makes it easier to send fuel to carbs and run a bit smoother at higher gears if the bike is fuel starved before but as before focus on the engine first.
MotoGB (real Hyosung UK importer) wants £200 for it. Used ones on fleebay can be hit & miss unless the seller guarantees that it’s been verified (they rod the bike before stripping) . Hyosung is not making new ones for your carb model as they are moving on to the EFi 125cc starting with GV125-S (no news on new EFi GT125 yet but even then their speed sensor wont fit yours)
But I may be able to get you one rapidly for less , depends how urgent it is! Send us an email.
Otherwise I have a fully working used one from a donor bike (it will be on ebay around Thursday/Friday for purchase)
Hyosung’s wheels are unique to the GT , and the speedo sensor also acts as a big spacer. Personally I have not tried other sensors front different bikes because I stock piled my own spares (Yes it failed on me too!) and plus there is cameras everywhere , i dont trust a china speed sensor to tell me its 30mph when the wheel is rolling at 38mph and i get flashed! I think OEM is best but have a spare copy yourself too!
If i ever discover and test a genuine japan suzuki speed sensor & fits on our wheels without needing calibration, I will make it known on this site!
Hope this helps ?
Hi mate sorry I have problems with email I tray to send an email to you Just wondering how do we’re proceeding for the item ?? Also I was wondering about few orders I put last week still waiting for news
What errors do you get ?
message me here temporarily until your email is fixed:
https://www.facebook.com/people/BrewMoto/61555775510442/Orders were shipped today (I was waiting for EBC to make new brake performance pads)
In regards to the Y-Bone , i meant the upside down U shape part that’s attached to the actual shock itself, it bends more than the old gen does, even slightly might throw things off. It has to be dead straight. if you must , there must be an NOS old gen shock or a good used one instead of trying the same newer updated one (it bends eventually)
