GT125R Cold Weather Death
- This topic has 28 replies, 2 voices, and was last updated 2 months ago by
.
-
Posts
-
-
Good afternoon to whoever is seeing this, hope you’re well. Two days ago my GT125R Failed to start on me, bump starts fail, my carbs are clean, but their were two cuts on the intake hose.
I removed the Vacuum pump, there was a significant amount of fuel inside.
Fuses are good from what I’ve seen, I’ve cleaned all the contacts around solenoid and battery, but I haven’t charged the battery to test the bike again with new hose lines and carb.
The bike continually fails to bump start.
There was a small amount of dirt and fuel on the front spark plug upon inspection.
Could it be a hydrolocking issue ? Due to damaged vacuum valve potentially leaking fuel into the cylinder?
Any help would be greatly appreciated!!!!
-
-
-
That’s a lot!
– How about we do this to stop any hydrolocking issues as that would mean a big disaster later!
- Remove the fuel and vacuum line going to the “TAP” on the tank , GET A BUCKET! , if fuel pours out….even a drip drip
Replace the tap! - If not, but when you crank the bike, with throttle closed (don’t touch throttle), fuel is dripping a tiny bit in to fuel filter
Replace the tap - If you are sure the tap is OK, then remove the intake manifolds (the rubber pipes going to engine cylinders)
Replace the O-Rings you see there
(LIKE THIS ONE)
These orings can also a LOT of vacuum loss sometimes, and this is why you have a hard time starting and the taps & pump are not opening properly due to vacuum loss. - If the O-Rings are ok , replace them anyway , and you will be alright for a good long while and use STAINLESS bolts on the intake pipes because it is not fun drilling out stuck rusted cylinder bolts!
- Open the fuel pump (see if anything looks broken inside) (if it says MIKUNI on the back, then it is Genuine) = > If suspicious or unsure, just replace the pump with a NEW one (I would not trust used pumps)
- The bike will start to hate running on the tap, so that’s why Hyosung put a pump on it. It is advised to put it back or get a new one and refit the vacuum lines properly again.
If having a new pump ==> Crank bike for 5 seconds max => You should see fuel SHOOT out of the pump going to the carb … this means TAP & PUMP are OK now…
If its doing “little drop” (*very little drops*) , then go back to my comments above again ^ before reading below….
We need to make sure the fuel system is actually sending fuel properly first… - Open the “OIL FILLER” CAP next to your clutch cover ==> Sniff hard, if you smell FUEL inside ==> drain oil & replace filter!!!
Use motul 7100 oil
If you need a tutorial
Click here - If the oil is fresh and good, you saved a lot of money and possibly broken crank!
- Get fresh CR8E plugs again (yes again) , don’t bother with CR8E-IX (blue box) , they are rubbish on 125cc Hyosung — Keep it stock or use LASER NGK
If both plugs are sparking WHITE-BLUE , the coils are OK
If plug is sparking faint colour => Damaged coil or HT Cap (NGK HT cap is better)
If replacing one coil , replace both (keep the old one as spare!)
Your plugs will thank you! - If you crank the bike, and plugs are WET from fuel ==> Coils , Cap , Stator , CDI problems
(Sometimes = Clutch switch will stop sparks , replace it here — DONT BYPASS!)
(sometimes “Kickstand Switch” is an ass hole, and it must be cut off from bike, it is very annoying…. Make sure the kickstand plug is “bridged” (bypassed)
Don’t forget to check stand before riding!!!)If kickstand switch is bypassed already , maybe water has got inside that plug and turned to rust, check those wires …. if CDI thinks its “missing” , it will not spark or cut sparks after 1st gear == make sure the wires are good there and water proof it hard from rain and salty wet road!
I can’t stress this part. - If fuse box has rusty fuse, replace it. No questions asked, that’s an easy 2volt loss there! use blue 15A fuse only.
Try all this and let us know of improvements ?
// Meditation doesn't mean you have to sit still....
- Remove the fuel and vacuum line going to the “TAP” on the tank , GET A BUCKET! , if fuel pours out….even a drip drip
-
Thanks for the fast responce mate
This is a video of me attempting to turn over without plugs in https://youtube.com/shorts/K_k-sZOfcdo?si=ydRsenRJ29BeK7-A -
This is a video of me attempting to turn the engine over with the plugs in https://youtube.com/shorts/7piyZbkzv_Q?si=i1j09LCl1BafOg8o
-
-
Sounds like you need to drain the oil out entirely (grab fresh one and fresh oil filter)
Next , go to the stator cover , remove it carefully and SLOWLY (the flywheel has a strong magnet) , so it might try to pull the case back in and also there is a “STARTER Motor SPROCKET” idler gear (looks like this)
Then once the cover is off (don’t forget to carefully disconnect stator plugs near the rear shock / regulator area) , put it aside nicely.
Have a BRIGHT torch, check the “Flywheel SPROCKET” (like this one) , spin it ONE direction and check for broken teeth,
Spin the sprocket the OTHER WAY
===> If it moves ==> Sprocket SPRAG CLUTCH is damaged
===> If it DOES NOT MOVE ==> Then the sprag clutch should be one.It should only spin ONE-WAY (sprag clutch looks like this)
if sprag clutch is damaged , DO NOT buy 250cc version. (it will not fit!)You could probably repair your old sprag balls, with this one….
Here is a full diagram of your starting system behind the flywheel…
This is your starter motor below
It sounds like in the video the starter motor is struggling to spin the engine (with or without plugs)
Having a replacement starter motor is not a bad idea 👍
Old Starter motors that spin too slow make it hard to start!
// Meditation doesn't mean you have to sit still....
-
Sounds like you need to drain the oil out entirely (grab fresh one and fresh oil filter)
Next , go to the stator cover , remove it carefully and SLOWLY (the flywheel has a strong magnet) , so it might try to pull the case back in and also there is a “STARTER Motor SPROCKET” idler gear (looks like this)
Then once the cover is off (don’t forget to carefully disconnect stator plugs near the rear shock / regulator area) , put it aside nicely.
Have a BRIGHT torch, check the “Flywheel SPROCKET” (like this one) , spin it ONE direction and check for broken teeth,
Spin the sprocket the OTHER WAY
===> If it moves ==> Sprocket SPRAG CLUTCH is damaged
===> If it DOES NOT MOVE ==> Then the sprag clutch should be one.It should only spin ONE-WAY (sprag clutch looks like this)
if sprag clutch is damaged , DO NOT buy 250cc version. (it will not fit!)You could probably repair your old sprag balls, with this one….
Here is a full diagram of your starting system behind the flywheel…
This is your starter motor below
It sounds like in the video the starter motor is struggling to spin the engine (with or without plugs)
Having a replacement starter motor is not a bad idea 👍
Old Starter motors that spin too slow make it hard to start!
Thanks for being so helpful friend, honestly.
I tried to bump start the bike. But engine just coughed abit and cut out, there was a slight hissing sound maybe, so ill change the intakes, carburetor and start motor. Smh
-
Just make sure you looik at your flywheel starting system cause if a part is damaged , it could flow loose inside motor and damage something else like a loose tooth! This will save you damaging another starter motor.
If we sort the crank first , then starter motor , and now we can move on to engine and electrics and fuel system using my comments from the 1st reply i gave you above ^
So follow it over & over again. If you finish my list correctly, you will learn something new to fix or make good progress.
// Meditation doesn't mean you have to sit still....
-
-
-
-
-
-
-
-
-
-
In my comments above ^ = Read it and let me know if the sprag clutch is working by testing with your hand and tell me what the BIG sprocket behind the flywheel is doing when you spin both ways
And which direction is it spinning (towards front or towards rear)
And which direction does it refuse to spin (towards front or towards rear)
Let’s just focus here first before i can address everything else.
The engine isn’t spinning properly that’s why.
// Meditation doesn't mean you have to sit still....
-
In my comments above ^ = Read it and let me know if the sprag clutch is working by testing with your hand and tell me what the BIG sprocket behind the flywheel is doing when you spin both ways
And which direction is it spinning (towards front or towards rear)
And which direction does it refuse to spin (towards front or towards rear)
Let’s just focus here first before i can address everything else.
The engine isn’t spinning properly that’s why.
It spins clockwise tonthe rear. Does not spin counter clockwise
-
-
Good, time to replace the starter solenoid relay and the starter motor too. Then the engine should spin faster
In service manual it says if engine spins to slowly , there is not enough cranking to start it properly
// Meditation doesn't mean you have to sit still....
-
Good, time to replace the starter solenoid relay and the starter motor too. Then the engine should spin faster
In service manual it says if engine spins to slowly , there is not enough cranking to start it properly
Gonna order the new parts on payday!, thanks for the help again. Do you know why it wont bump start ? Havent been able to get the intake manis off due to worn bolt. But everything seems okay
-
Newer Generation 125 engines & their electrics (RC / P models) , don’t really like bump starts and are VERY hard to start if it feels like parts are not in spec.
~if you try to start the bike with Jump Leads of a RUNNING CAR/VAN = It will never ever start again, bike is too fried.
If you want to use a car or van to start = Remove the battery out of the car / van
or i would recommend to just get a “Motorcycle Charger” (not a car one!) and charge the bike battery , weak batteries make it hard to start too.
I am digressing , but i hope that made sense.
// Meditation doesn't mean you have to sit still....
-
Newer Generation 125 engines & their electrics (RC / P models) , don’t really like bump starts and are VERY hard to start if it feels like parts are not in spec.
~if you try to start the bike with Jump Leads of a RUNNING CAR/VAN = It will never ever start again, bike is too fried.
If you want to use a car or van to start = Remove the battery out of the car / van
or i would recommend to just get a “Motorcycle Charger” (not a car one!) and charge the bike battery , weak batteries make it hard to start too.
I am digressing , but i hope that made sense.
Im refereing to a running bump start sorry, to get the engine turned over manually. I bought a new 12amp batt like you said also.
-
-
-
Hi Marcel, hope all is well. When attempting to start the bike, no fuel leaves the tank. I also used “mannol 10w40” intsead of the recommended oil. Im going to put a new oil, fill up the tank and attempt to start again.
Low vacuum (intake oring leaks) as per my earlier comments above ^ (or just see this link directly below)
Or tap issues.
And yes as long as the oil says JASO MA2 for motorcycles (certification) otherwise it may be car oil & you will have a lot of issues later. If it’s bike oil, i would replace it after 500 miles and use motul. It sounds crazy but most people who say “any oil is fine” are the ones you wouldn’t want to hear their advise on serious matters anyway lol
// Meditation doesn't mean you have to sit still....
-
- You must be logged in to reply to this topic.