Gt125r not starting
- This topic has 20 replies, 4 voices, and was last updated 2 years ago by
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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.
// Meditation doesn't mean you have to sit still....
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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.
// Meditation doesn't mean you have to sit still....
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Is there any motorcycle electricians neer bradford as i dont have a clue why my bikes not sparking . Side stand stand switch . Clutch switch . Neutral switch all seem to be working. charging phases seem to be ok as ive done test i saw on youtube.dont no how to test rectifier. Ignition relay seems to be letting juice through please 🙏 anyone help.
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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 ?
// Meditation doesn't mean you have to sit still....
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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!
// Meditation doesn't mean you have to sit still....
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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!
// Meditation doesn't mean you have to sit still....
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Ok will do thanks.
Check your PM fella. About your order on the way to you . Thanks!
// Meditation doesn't mean you have to sit still....
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Thanks to Marcel and Simon. After fitting upgraded stator & flywheel, coils and rectifier bike running better than ever uprated sprockets makes a world of difference
.Hello Dave,
I am very happy for you!
If it is not too much trouble for you, check the stator and reg pages on the shop and go to bottom for “review” section and leave some feedback. It lets everyone know how it actually performs from your own point of view , they can’t just take my words for it 🙂Especially with the 520 chain kit (if you got it from us recently) , leave some review to see what changes it did from stock setup , ie. 1st was 20 oem , but uprated was 15mph (faster) or 30mph (slower but each gear range is extended), or balanced etc etc.
Look after her fella 🙂
// Meditation doesn't mean you have to sit still....
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Hyosung gt125
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