Gt125r engine cut out
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Im currently having an issue with my bike at the moment, when the engine is hot my bike seems to cut out and i’m not able to put any revs on and it falls down to 0 rpm, then once the bike has cut out it will take around 5 mins for it to start again and you can ride it like nothing ever happened, i dint know whether it’s running to rich or something but i’ve tried adjusting the idle but that hasn’t helped, any suggestions would be great
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You can do this right away to help the bike long term
- Motul 7100 oil (strictly this , nothing else) – Get “10w50” grade instead of 10w40 (10w50 is allowed by hyosung)
Also it takes longer to break down , hence good quality oil i recommend it
Fresh oil filter (always) - Upgrade ignition coils (OEM ones on 125s tend to break down)(Common)
- Upgrade to NGK Caps (Better heat resistors) (OEM ones are made by GOLDEN company in China. Cracks a lot inside.)
- Check to make sure Regulator is 14v from idle. = If no, Korea says replace it right away.
- Check to make sure Regulator is 14v at 5,000 revs = If no, replace it.
Fuel System
Tell us below, first ….- have you replaced the fuel tap under the tank (too common) = No fuel or too slow –> Your carb drains its bowls and bike cuts off.
- Fuel pump – New one is a good idea, no rebuilt kits for it exist yet. = Slow dying pump means its prone to cut outs.
- Upgrade to fuel lines sold at this shop and it’s monstrosity filter
Hint = If the filter is HALF full when you finish riding , tap is doing OK
Hint 2 = If filter is Half-Full at 6pm —–> and at 10pm its emtpy === DO NOT RIDE the bike! (Your floats, pump, etc need check as they allowed fuel in to cylinders
Engine hydrolocks
And soon damaged piston rings with excess heat.
Just too many problems later. - USE E5 ONLY = Sorry for all caps but E10 really is a killer. If you use E5, then well done 😉
Carb System
This monstrosity is happiest when its had an ultrasonic bath and a wizard that’s tuned it properly to the tee. If a mechanic tries to tune a carb by “guessing” , do not pay him & don’t use him again.Sometimes tuning also involves checking float height is 7mm upside down
Carb Rebuild Kits include a float valve that actually has a “spring” on it, which can be dead on OEM floats after many years, hence if there is float issues = soon cut out and stranded.
If in doubt, just get new floats at the shop too & don’t adjust them.
Engine Heat = 100000000% recommended to get a 250cc oil cooler. It will love you for it.
We have more than 10x oil coolers for sale, just send us an email. Some are on ebay under the @Evocrest name with protective grills sold separate.Summer is coming.
Cool down that hot girl 😉
- Motul 7100 oil (strictly this , nothing else) – Get “10w50” grade instead of 10w40 (10w50 is allowed by hyosung)
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i’ve only just got the bike and i haven’t changed the fuel tap, it’s currently in a workshop and they’re looking for a fix
Let us know via email if the workshop needs anything from us but i suppose they should you and report back here their findings (They better do the work right and not treat it like its china scrap)
Good luck!
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hiya marcel i’m sorry to bother again, the bikes been in at the garage for over 2 weeks and have just got it back today, they fixed a few things-
fixed an over pressurising fuel tank
changed plugs/ coils
valve clearance/ carb balance
i rode it when i got it back, seemed fine until i did a top speed run where it cut out at high speed, im so stuck with it and any suggestions will do
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hiya marcel i’m sorry to bother again, the bikes been in at the garage for over 2 weeks and have just got it back today, they fixed a few things- fixed an over pressurising fuel tank changed plugs/ coils valve clearance/ carb balance i rode it when i got it back, seemed fine until i did a top speed run where it cut out at high speed, im so stuck with it and any suggestions will do
Fuel Tap wanning (common)
Fuel Pump wanning or needs a minor clean
Fuel Filter clogged or facing wrong way
Carb Needs *optimizing*
2 weeks just to do clearances and optimize a carb (apparantly). They are taking the piss as i would have had it done much sooner.
Also explain a bit more about this top speed run?
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i went on the bypass and got up to sixth gear and was sitting at around 10k rpm for about 3 minutes then i felt a loss of power then i couldn’t get the revs up and came to a complete stop
Thats the one!
Assuming you have upgraded all electrics (due to heat failure / common) (coils, caps, laser plugs not IX junk ones, stator, reg rec)
Then your war is slow fuel delivery issues vs high speed runs. In other words my previous comment says the bike is asking for fuel faster than the entire wanning fuel system can keep up.
As such. You might want to look at ur plugs or show us.
Also take a look at the other thread on homepage that says *MOT & Running Issues* there is recent replies which could help you in regards to your thread also.
Let us know if in doubt or have questions on this topic.
Its not dead. Just a little moody as it wants off the leash 😉
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my dad wants to know how to do the fuel cap vent fix, any suggestions?
Inside remove the fuel cap off the tank (unscrew it)
Then look for a hole thats near the bolt holes. That is overflow/breather and drains away to the long pipe under the tank that dangles near the shock.
Keep that clear or spray air compressor. You will hear air hiss out of the super long overflow pipe.
Check the fuel cap unit by pressing its springs down and see if they come up smoothly. There is no rebuild kit for them. So if its suspicious or packed it. A replacement is advised.
That is also a good question from him 👍
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This has been a suspicion as whenever i open the tank after riding you can hear the pressure escaping so my dad thinks there is a vaccum being created which is causing it to cut out.
Try the hot fixes i mentioned above and see if the situation improves before its time to replace the unit
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We have success, replaced the fuel cap with a GV650 one and its running better than ever with no spluttering, bogging or cutting out around 400 pounds in attempts to repair when it was just a 20 pound fix
Hey, it can’t be all waste if the bike rides better with some new goodies that you won’t have to worry about!
I’ve once bought a bike needing a fuel tap, but i was like screw it, let me overhaul the entire fuel system including its injectors , the result was that i didn’t touch its parts for 2yrs as it just kept on going.
if i just fixed the tap, what if the injectors were next to go pop! – Sucks to have a skinny wallet but i am smiling more when it doesn’t break down on me 200 miles away from home. I could be clinically OCD about such things lol
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