♠️ M77
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Me too , i don’t like like the sound of single thumpers whatever the size it is lol. 2T will be an exception.
You can always buy 2x RS125 bikes and one is a future spares donor, buy another engine too. Then you should be okay.
As for the hyosung, hills & winds = 520 kit and improved clutch will help you for sure.
I don’t know about you but damn , that white center isn’t good, it suggests bike is leaning out full throttle.
Here is a picture of an old customer of mine , his bike as factory brand new. He did not touch anything and he is the only owner.
The carb was 3 to 4 turns from factory , standard jets, everything was standard on the bike. No mods.
It was annoying to start in winter sometimes.
Threads of spark plug is a bit yellow ish = engine hot (a tiny bit too hot)
oily threads = crap gasket inside rocker cover.ARCH of plug is okay = piston chamber heat is okay.
Center is brown ish = seems okay full throttle
Circle Ring is black, sooty = rich idling.
Next below is one of my old laser plugs. I was OCD with the bike , i got a little obsessed with trying to get an “ideal brown color” on the plugs.
These plugs are 2 years old.
The BDS26 carb has ability to power even a GS500 or maybe an old suzuki i4 (inline 4) with 15 pilots (up to 600cc maybe) , but 30 pilots ? Even the carb 250cc Hyosung is perfectly fine with 20 pilots it uses, mixtures on the 250cc would usually be 3 turns or little less from factory.
Not ideal i know. All stock carb bikes can be tuned 😉 – – If the 250cc (250cc?) can live with BDS26 carbs and same airbox & same air filter, i don’t think a 125cc will ever max out the capacity of the carb, so factories fit smaller jets. And sometimes downtune (downgrade?) the carb to meet 14HP laws in some countries. & emission control (Euro 3 crap)
However i do KNOW , using 250cc intake pipes on a 125cc engine helps with throttle response! (250 intake pipes have a bigger hole) and is much shorter , so carbs are much closer to engine with less travel around the manifold bends for air.
The 250cc airbox is required for this but its okay , its a little deeper than 125 (more room inside for air)
Have you perharps tried size 17.5 pilots ? and check your spark plug colours (from new or fresh clean)
At pilot 30’s , what is the mixture on the carb how many turns is it ?
It could be your climate and altitude where you live at , but here in UK , 15 pilots on the 125cc is the gold standard. The 4-7k rpm flat response is improved by ofcourse fine tuning the slide needle with larger main jets (1 size up front and rear main jets)
Ok will do thanks.
While you wait for those things….
Get your meter out….
Stage one = Switch to 20K ohms
Ground frame (meter -) & HT wire (meter +) = Ohms ?
Switch to 10 ohms (Ten)
Ground frame (meter -) and & Coil Terminal Spade = Ohms?
Now you have tested Secondary and Primary Resistance of the coil. Tell us and we will advise if the coils are in OEM spec or not.
Next…….
Remove HT Cap from the coils (unscrew anticlockwise)
—> Switch to 20k ohms
Meter (-) in one end of the HT cap and Meter (+) on the other end of the cap.Tell us the ohms of the HT cap by itself without any coils attacted to it.
I have a funny suspicion that the harness probably needs a thorough inspection (hard to do while its still on the frame) , it’s a long sucky day taking it off but…….
– Get mannol tape = And overtape the whole harness. It’s a very good tape! (Mannol Harness Tape)Korea’s own tape for the harness is not that great on carby bikes. and the wires easy get frayed or grazed up on the chassis if they get exposed (if they get exposed enough, they get chaffed , and if a naked copper line is exposed, it shorts the fuse or does something to the bike that it gets harder t start next time (as it’s annoyed)
– Get Halfords Contact Cleaner = Get crazy with it until you see your pins free from muck. = Dirt, debris inside plugs = No signals can pass thru , bike won’t start in some cases.
– Euro Carparts , Amazon PRIME 1 Day, Halfords = get ACF 50 = “whatever plug” , i mean “any plug” on the bike , add a very tiny drop of ACF50 inside and it will thank you for preserving its pins , sometimes “oxidization” happens inside plugs. Yes you can even ACF50 the battery terminals.
Do NOT use WD40 or any other substance = It will guarantee flames go up soon.
You should have your clutch switch by now.
Next , what else cuts sparks off besides loom?
– Side stand switch (bypass it, ) if yes already then good! = But remember the area that’s bypassed (ie at the plug , could have debris , double check it. It is very cruicial. Most newer 2015+ bikes that have trouble starting is because of this stand bypass being done poorly by last keepers)Hint = If sidestand bypass is not active or side stand switch is not there, the “WHITE RPM DASH” will not move at all ….. It stays “zero revs”
Hint 2 = If there is sparks , the RPM gauge will start moving up, 0, 2, 3, 5, 7k rpm (in a funny fashion) then bike fires up
(Don’t worry the starter motor still spins at 500-700rpm)Hint 3 = Rpm needle is moving up, then sweeps down , moves up , while cranking = You have no fuel coming out. So bike is dry sparking.
CDI = Can cut sparks off when its fautly , can’t start without it. However , it should be fine , it will be the LAST object to worry about.
Stator = “Pickup sensor” (2 Pin Plug) from the stator is the “beginning” of the sparking system. = GT125RC stators are quite smaller , 18 pole units , they usually have the pick up values similar to EFi bikes (80-110 ohms is good for the carby 125 in general)
Upgrade ones (would be around 120-140 max) , (as was the case in old gen carbies)Yellow wires = charge system = Beyond 1 ohm on any yellow wire ice cold means the stator is on the way out. Normal range is 0.5-0.9 ohm on a single yellow wire and the 3 wires must have identical values (if one wire is out of spec, the whole 3 phase unit is not good)
Hence Simon cautioned to have a good regulator next too. Stator & Reg usually go hand in hand (married). (as is the Ignition Coil & HT Cap need each other but a faulty HT Cap with a good coil means no sparkings or temperamental bike)
Clutch Switch = On the way, this cuts sparks off anytime the bike is running or turned on , this switch must work at all times.
Neutral Sensor = If this unit is faulty , the 2017 bike doesn’t want to know. It won’t spark.
Out of the bikes i usually fix , the New Shape 2014-2018 GT125s are notoriously hard to start , if they sense even one small thing out of place , the old gens can even fire on one cylinder and force themselves to start surprisingly or bump start easily in to 1st gear after a rider is pushed a few yards around in the yard.
I am digressing, i hope this helps!
I really hope you keep that bike, it looks really sweet and being the 1st owner of it , i think you would be silly to divorce it 😉
Any plans for the hyosung ? Considering you have had enough experience on 2 and 4 wheels to probably modify anything at this point lol.
Would this fit a 2009 GT125r If in doubt , get the trusted one from EBC UK , they make discs for hyosung. If in doubt, ask the local bike shop as they will usually have a trade account to get EBC pads, so ask them to get you locally an EBC disc for Hyosung GT, if its urgent for MOT etc. I usually have discs on ebay but used though with life in them, that’s a little cheaper than me ordering a new one for a client quickly.
125, 250, 650 = GT and GTR = Same discs. Up to 2019.
250 cams are heavier than 125cc and ofcourse they are thicker and have bigger egg lobes , so they may “press” down the cam buckets a bit further in to the cylinder so the valve could hit piston or just about “miss it” . Risky gamble but can try it.
Another problem = extra weight , more load on valve springs and slim cam chain. The 250 uses much fatter cam buckers and thicker chains ofcourse.
The sprockets of cam shaft may be removed , and use 125cc cam shaft sprockets to keep using the 125cc chain. However be warned on accelerated wear on valve parts, so frequent inspection may be advised.
250cc and 125cc vtwins have the same timings and same clearance, so i would not expect big performance gains. The most costly part in the engine is the crankshaft, so have to make sure crankshaft teeth of the 125 don’t get extra stress.
Just my thoughts 🙂
What happend to it ? Perharps i can repair the switch block for you ? Just send a PM and post it to me and i will see what i can do
If possible, post a picture here as to what damage is on it and such.
Ignore testing to the ground of the frame. This would be ideal here;
2PIN plug = under 200 ohms. See what it says.
3Pin Plug (Yellows)
Pin A & B = Ohms ?
Pin B & C = Ohms?
Pin C & A = Ohms ?Report back. Also check your PM please, i have responded to it.
This thread can stay open , so i won’t close it , if you get a break through, then great!
JMP Shims are better. Supposed to be made in Japan too. Go OEM Suzuki or OEM Hyosung if you can (Hyosung uses Suzuki’s shims anyway)
I have not tried HotCams or ProX to comment on their wear rate and such.
Why not get the GV125 and fully rebuild it from the ground up even cosmetically because here in the UK, they always sell around £2000 mark but usually no less than £1000 if its tatty (cosmetically rought) but bike works as it should.
I would tell the seller the bike is worth £250 in my eyes, a rusty tank is not good but depending how bad it is , i won’t be able to say now if its worth trying to save it (taking rust off by chemical means) or buying another used copy tank but repaint it. etc.
I suppose if the batter is accessed and the carb was cleaned (ultrasonic bath etc), change oil immediately of the bike, then new plugs, see if fires up to life.
I do agree the GV125 is chunky for what it is , but ofcourse same body as the bigger GV250 sister. The GV650 is much bigger.
If you dare ? Get the GV125 and work on it. And use the Yamaha as a pleasure or commute bike for the time being, it will fetch some money back when its time to sell it.
As per Simon.
If the situation is serious send a PM or email , as we’re in Yorkshire already so we may try fix the bike.
But for sake of simple tasks , it’s better and costs nothing if you do it yourself patiently.
When cranking the bike, does the RPM needle move ? or stuck at dead zero ?
I will try to find one for you during the week at my workshop for you!
Hi sorry I can’t seem to put a picture on. Sprocket with smooth side facing away from the engine. I did use impact driver with no chain when removing Sprocket could that have moved something. It turns over fine just no spark.
Try the replies me and simon have mentioned and report back if you checked those electric parts.
The “Hump” of the sprocket should be facing you as this is the correct orientation and the flat-side of the sprocket should face the crank case wall towards the clutch cover.
If you can’t get a picture in, just let us know what error the site makes or what it’s doing so i can make it better 😉 even what phone/pc is being used.
Good luck, you got this! – Remember it turns yes, but things that me and simon talked about are what’s cutting sparks off , unless you have a deeper issue but basics above ^ first and let us know.
If its a barn find, it will mean straight away an ultrasonic clean of the carb and do check the tank doesnt have rust inside , and as safety measure , replace the fuel tap too.
MPG wise i would say the 125 will have a slighly better MPG than a carby 250 does due fact less piston size , and lesser jetting but still lives high rpm life>
ie. 10k revs in 3rd gear for 40mph in 125cc, the 250 would achieve that in less reves, just an example (not accurate, just a guess)Fortunately it’s easier to change gearng of the 125 in to cruise mode to use less revs and a bit less fuel , by upgrading to a 520 chain and sprocket set. The slim 428 chains aren’t worth wasting too much money on a heavy bike that will stretch and vtwins by nature start their power at lower revs than a big cc inline 4 bike.
Go get the 125 🙂 , and ofcourse ignore whatever the previous owner did to , always assume its 0 miles (no matter how old it is) and be ready to give if a fresh overhaul of servicing from the get go , usual like tyres brakes filters , fuel lines, suspension checks and all that stuff. if you dare , stripe it down to bare frame while leaving engine inside and just clean up the parts with a nice drag and wipe down the frame from any mud, road traffic film and or oil spills from oil changes or chain grease gunked up inside sprocket cover with a good de-greaser
Changing a chain has no effect on electrics whatsoever , unless can you show us the front sprocket please (so i can confirm its facing right way or there will be a big oil leak when it runs)
So since you are near the front sprocket , check neutral sensor wasnt the hit or its cracked up etc and check wires as its under front sprocket
if the finds suspicion with neutral sensor , or side stand (even if bypassed, rusty wires loose their signal) , or clutch handle bar lever switch (don’t cut the clutch off please, just replace the cable if its a culprit)
it is there to save ur gearbox , some 125s actually start in GEAR (even if it says neutral) , then bike falls to the ground. So the clutch switch is there to force rider to hold it in as you start it .
Halfords Contact Cleaner is very good to help clean rusty pins inside every plug.
Any bike shop or Amazon PRIME 1 day = Get “ACF50” , spray a tiny tear drop inside every plug you see on bike It will love you for it.
Do not put WD40 on electrics unless you want a big fire.
trying to find emulsion tube bolt for2008gv125 any ideas or does anybody have used carb for spares
Post a new topic of your own and please include picture uploaded to your new post, as it helps a ton.
Filter to the PUMP = that short upgrade hose, you can cut it down a little more so the filter doesn’t feel kinked up 🙂 , just a tip!
