2016 GT125R – Rough idle, accel, not charging
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Hi all,
Recently picked up a GT125R in decent condition. Chap who sold me the bike said it wants a carb adjustment, but beside that everything is fine.
Rode it 100 miles home, all good, a little boggy when going through the gears but managed to get up to 70 none the less.
Noticed on the evening that my battery was flat and I couldn’t start the bike without bumping it into second. Swapped the old one (12v 150a) out with a Yuahasa 12v 200a battery from Halfords, seemed to work just fine.
A day later, same thing again, bike doesn’t seem to be charging when riding which has made me think the regulator is knackered?
Also bike won’t idle without a small amount of throttle being applied. I assume this is because the carbs need taking out and looking at? I’ve just been running Redex through it until payday, as its my only form of transport.
Any ideas? I’ve browsed some solutions on the forums and I’m considering buying the regulator upgrade to see if this remedies my problem. When I used a multi-meter on the terminals, it was reading around 12v, even when applying throttle.
Kind regards,
RJ
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Post above isn’t great, writing on mobile so apologies in advance.
So the issues I’ve identified so far:
– Can’t start without full choke.
– Can’t idle without throttle held at around 1-2k RPMs when choke is off.
– Battery isn’t charging whilst riding.
– Fuel indicator constantly flashing empty, even when tank is filled.
– Bogging/Sluggish acceleration, doesn’t sound healthy.
– Rubber inlets are worn, small cracks visible but only seems to be surface level. They’re 7 years old, so not surprised.
What I’m considering:
1. Remove carbs & give them a proper clean out & make sure everything is in order.
2. Upgrade the regulator with the one from the shop.
3. Replace rubber inlets with custom-made metal ones.
4. Upgrade stator with shop one. (Will have to purchase this following payday, as money is tight.)
5. Swap out plugs & caps with NGKs as recommended, along with iridium spark plugs.
This forum has a wealth of knowledge and I do appreciate the wizards behind it, but would love some additional support.
Have I missed anything? And how would I remedy a dodgy fuel level read on the dash?
If anyone is based in the Midlands and could give me hand, I’ll be happy to sort you out.
Cheers,
RJ
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Hi I think that the the first step is to ensure that You have a proper voltage try with the regulator/rectifier first al cleaning and servicing the carbs it Will take an hour or less depending of what you find also, you can test You regulator with a multimeter and descart it here is a video to test it
And just un case the regulator pinout
You can Even adapt another three phasic regulator just be sure it’s treephasic
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Hey,
Midlands to Yorkshire is a bit of trek for you to come isn’t it ? 😉
The upgrades you said are recommended yes. I would add my 2pence below to help you:
- Get a multi meter -> Disconnect Fuel Sensor – > Put the meter in to max 300 or 500 ohms level (five hundred) and tell us the reading you get and i will confim if the sensor is dodgy or not. Also tell us if the tank is half full or very full
- Go to halfords -> “ONLY” , i mean ONLY get this product and use it forever (Hyosung’s do not like redex)
https://www.wynns.uk.com/product/formula-gold-fuel-system-treatment/ Usually we use a full bottle on a full tank , just to make the cleaning process a bit more agressive , ride until the fuel gets low.
Allow the bottle to collect muck, dirt , etc and it will burn away at the exhaust.This is like a “temporary” soft clean of the carbs too.Get ACF50 and PUTOLINE RACE GREASE on amazon = Make sure “anything outside the engine” that moves and gets attacked by crap being thrown by the wet tyres , grease it.
ACF50 is for the entire bike with a cloth , wipe everywhere metallic except brake discs to leave a nice layer of ACF50 anti rust treatment.
See the plugs under the oil cooler ? _ Yes , drop the oil cooler from the frame, leave pipes connected and add a little drop of ACF50 inside EVERY plug there)
Then hide the plugs with this below (it is called SUZUKI HARNESS BOOT)
You harness will thank you
ACF50 again, find any connector on the bike that’s exposed to the weather and put a little drop of acf50 inside there.
Buy another Suzuki Harness Boot to hide the stator plugs near the shock
Buy another Suzuki Harness boot to hide the indicator wires behind the rear pillion seat.Ring FOWLERS UK BRISTOL (Genuine Suzuki Dealer, ask for exactly what i said as its used in various suzuki. They call it “Harness Boot”)
DO NOT USE WD40! – It will instantly go on fire lol. Only ACF50 should be allowed on the electric plugs/terminals.
- Regulator = 100% got to go.
- Stator = Test your old one first both in voltage , and also OHMS when it has been overnight cold. = before it fries the next regulator. At this rate you have been running on the battery itself , the regulator should be absolute minimum of 13.5V as per hyosung rules but ideally 14V to 15v max up to 5,o00 revs.
- Test your coils = If they are retrograding or acting wishy washy , it will eat your spark plugs and will explain the boggy behaviours while running.
NGK Caps yes good investment, they rarely ever fail tbh.
If you want to be fancy , go to amazon and get 7mm thick MAGNECOR HT WIRES too (that will make a nice upgrade between a beefier coil & ngk cap)
Keep us posted , and please let me know if missed something too, and ill edit anything i said or reply with new information.
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Thank you for the swift replies gents.
I’ve got a friend taking a look at the bike on Friday, should be hopefully giving the carburettors a good clean & checking over for any other issues it may have underneath the fairings/airbox. I’ll report back on any findings & if messing with the carbs makes any difference come the evening. I’ll be going through the suggestions above with him.
Honestly Marcel, if coming to Yorkshire means my bike gets looked over by someone who’s familiar with these machines, I’d be more than willing to make the journey as your knowledge is invaluable.
Rj
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Honestly Marcel, if coming to Yorkshire means my bike gets looked over by someone who’s familiar with these machines, I’d be more than willing to make the journey as your knowledge is invaluable. Rj
Don’t stress, Enjoy the Easter fella. I think we will get somewhere , but please tell him NOT to mess with the fuel mixtures and if the bungs go missing you will have absolute hell trying to retune the carbs
Put these in your basket!if he needs gaskets for the floats (without extra bits, let us know, we might have some)
No need to ride up here, it’s better to send it on transport or we will come and collect it. If push comes to shove. if it is your means of transport and can’t bear the thought of leaving her with us for a while , then i pray the local man looks after it properly and doesn’t cock things up (or he pays!)
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Update: (apologies for formatting, written on mobile)
Just got back from my friends and it’s running much better than before. Acceleration is smoother, it doesn’t sound nearly half as unhappy and she can now idle rather than stalling out.
We opened her up and took out the carbs, gave them a solid clean using plenty of break cleaner, unclogged the jets and that seems to have done the trick.
She had an issue with the air to fuel ratio, and we’ve temporarily remedied it by drilling a small hole in the bottom of the air box to help her breath a little better.
Replaced the plugs with Iridium NGKs, the front block was a fun one to figure out.. 🙃
There doesn’t appear to be any rubber bungs in the carb adjustment screws which leads us to believe that it has been tampered with before, so to have the bike running 100% I’m going to have to get them aadjusted by a professional.
The new battery I fitted a few days ago hasn’t died since charging it, so I believe I misdiagnosed the reg/stator. We ran the battery dry today constantly starting her up during the testing process.
Jumped the bike off another battery and it maintained power after the ride home, so happy days.
So I’m happy, the bike is in a much more rideable state and touch wood, everything seems fine.
The last demon to work out is the fuel level sensor, its currently flashing on empty. I traced a yellow wire from the loom that plugs into the tank and blasted it with break cleaner but that didn’t seem to do the trick unfortunately..
Thank you for all of the advice, it is much appreciated.
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Attached a picture of the carbs for reference. We didn’t tinker with these screws, so if this is where those bungs are supposed to sit, they were already missing.- You must be logged in to reply to this topic.